REP  0  R  T 

*y 

Prof.  Comm.  G.  Fantoli 

on 
ROCK  FILL  DAMS 

1918 

Translated  by 
M.  M.   O'Shaughnessy 
City  Engineer  of  San     Francisco 
19£0 


UNIVERSITY  Or  CALIFORNIA 

DEPARTMENT  OF  CIVIL  ENQINEERIMG 
BERKELEY.  CAUFORNIA^ 


MINISTRY  OF  PUBLIC  WORKS 
Supreme  Council  of  Public  Water-Works 

Prof.  Coram.  ^.  *'ANTOLI 


REPORT 
to  the 
SUPREME  COIMCIL  OF  WAIER-V/ORKS 

concerning 
THE  ARGUMENT  ABOUT  ROCK-FILL  HAMS 

and 
THE  PROBLEM  OF  THE  RESERVOIRS  IH  ITALY 


ROME 


Press  of  the  "Unione  Editrice" 
Via  tfrederico  Oesi,  45 


1918 


INDEX  page 


American.  Soo«  G.  E.,~ 

Dams,  earthquakes, 

Morena, 

Biographical  references  of  Luiggi's  writings, 

California  laws  on  dam  construction, 

Comments  by  M.  M.  O'Shaughnessy 

Conelusive  allusions  to  rode  dams, 

Concrete  dams,  Thermic  argument  on, 

Cromwell  on  Lower  Otay, • 


••••»«•*••««••.*••« 


Dams:- 

Arrow  Hock  • 47 

Australian  Dams,  50 

Bear  Valley,  48 

Big  Creek, 46 

Crystal  Springs,  38 

Eagle's  ITest,  49 

Elephant  Butte,  47 

Esoondido,  72 

Gatun,  18 

Hetch  Hetchy, 49 

High  dams,  Heclamation  Service  51 

Jadkin,  49 

Klaraith  River, .  •  48 

Lower  Otay,  rock  dam,  21 

Morena,  14 

North  Yakima,  ...• 49 

Piedmont,  37 

Portola,  38 

Hock  Creek 43 

Salmon  Greek  49 

San  Andreas,  35 

San  Leandro,  Je-nescal, 37 

Spaulding,  48 

Strawberry,  15 

Upper  Crystal  Springs, 36 

White  Salmon  River,  48 

Earth  dams  and  earthquakes, 32 

High  Dams,  Reclamation  Service,  51 

Masonfry  Dams  and  earthquakes  38 

Rock  Dams  and  earthquakes 27 

Thermic  argument  on  concrete  dams,  74 
Earthquakes:- 

Am*  SOO.  C.  E., 34 

Earth  dams,  35 

Masonry  da^ns,  38 

Rock  dams,  *............  .  27 

Engineering  iJews-Record,  Data  on  darns,  45 

European  texts  on  dams, 43 


INDEX  (cont'd) 

Fantoli's  notes  of  objections  to  rock  fill  darns 
Foot  .uotes, •• 


French  technical  System  64 

Place  of  France  and  Switzerland  on  dams  62 

Index  of  writings,  Professor  Luiggi,  on  rock  fill,  12 

Italian  situation  on  high  dams,  41 

Land  areas  and  population  density,  Italy  and  U.S.,  52 

Laws  on  dams, 

California, 55 

State  of  New  York,  56 

Lower  Otay  Dain:- 

Gromwell  on  Lower  Otay,  66 

Discussion  of  failure,  66 

Failure  22 

Literature   .  22 

Rock  fill,  21 

Luiggi,  Professor :- 

Biographical  references  of  writing*  43 

Indes  of  writings  on  rock  fill,  12 

He commendations  -  rock  fill,  2 

Refutation  of  Luiggi *s  rock  dams  predominance,  38 

Morena  Dam,  14 

Objections  to  rock  fill  dams, 7 

Overflow  on  rock  dams,  65 

Place  of  France  and  Switzerland  on  dams,  62 

Reclamation  report  1916-17,  pages  453-4  on  Storage  dams,  51 

Rainfall  distribution,  San  Diego,  75 

Reclamation  Service,  high  daoia,  51 
Be commendations,  Professor  Luiggi, 

Refutation  of  Luiggi *s  rock  dams  predominance,  38 
Reservoir  problems  in  Italy, 


BIDEX  (  cont'd  ) 

Page 

Rock  Fill  Dams:-  27 

Earthquakes, ....» 27 

Overflow,  65 

Lower  Otay,  66 

Secondary  arguments  relating  to  rock  fills,  72 

Luiggi ' s  re c ommendat  i  ons ,  2 

Objections  to,  7 

Index  of  writings,  Professor  Luiggi, 12 

Conclusive  allusions  of,  79 

Morena,  14 

Spillways, 74 

San  Diego, 

Rainfall  distribution,  75 

Runoff  discharge  per  square  kilometer,  76 

Secondary  arguments  relating  to  rock  fills,  72 

Spillways,  rock  fill  dams, ••• 74 

Ihermic  argument  on  concrete  dams,                         .  74 

Comments  by  M.  M.  O'Shaughnessy, ••• 90 


Concerning  the  Argument  about  Rock-Fill  dams 

and 
The  Problem  of  Keservoira  in  Italy. 

Erroneous  propositions  of  a  one-sided  propaganda  and  the  inherent 
perils  of  it. 

Necessity-  of  the  present  decided  reaction  for  the  safety  of  our 
valleys,  and  also  in  the  future  interest  of  Reservoirs  in  Italy. 

1.  Chief  characteristics  of  the  propaganda  in  favor  of  the  Rock  Dams  - 
Incentive  for  the  present  writings, 

She  vote,  Dec*  30,  1916,  of  the  Supreme  Council  of  the  L.  L»  P.  P. 
gave  its  sanction  to  the  official  construction  of  Rock  Dams,  even  of 
great  height.  It  is  a  remarkable  fact  the  Honorable  Prof,  luigi  Luiggi, 
an  authoritative  member  of  the  said  Council,  also  of  ottb  Council  of 
Water-Works,  and  chief-Inspector  of  Rivil  Engineering,  is  a  most  active 
promoter  of  this  Rock  Fill  Dam  construction. 

(Bhis  vote,  if  I  do  not  wrongly  accuse  them,  admitted  intentionally 
just  the  simple  proposition,  thus  giving  free  scope  to  the  projects  that 
overcome  the  conventional  altitudes  which  become,  as  .a  matter-of-fact,  a 
consideration  of  the  technical  value  of  the  flow  capacity.  Under  given 
conditions  it  might  be  permissible  to  build  Rock  Dams,  in  some  places, 
30  meters  high,  while  in  others,  those  of  15  meters  should  not  be 
undertaken. 

But  the  propaganda  of  the  brilliant  apostle,  (Luiggi]  is  based  on 
only  a  few  sources  of "information,  which,  according  to  me,  are  entirely 
useless,  being  based  on  inspection  not  altogether  impartial  and  positive. 
These  characteristics  constitute  at  once  the  strength  and  also  the  weakness 
of  the  said  propaganda.  As  proof,  I  will  give  quotations  and  I  shall  need 


to  cite  many  in  these  pages.  Here  it  is  sufficient  to  announce  that  the 
absolute  predominance  of  Hock  Fill  Dams  is  asserted,  without  the  least 
suspicion  of  a  doubt. 

They  place  among  the  antiquities,  in  regard  to  their  application  in 
cases  of  notable  height,  the  type  of  Dams  with  "gravity  section"  -  "which 
are  for  this  reason  to  have  no  imitators  in  the  future",  More  recent  con- 
clusions are  found  in  the  followii.g  terms  ;- 

"The  lock  Pill  Dams"  represent  the  ideal  for  the  high  mountain 
regions  and  also  for  the  sections  subject  to  seismic  shocks;  that  is 
they  can  efficaciously  resist  contigencies  arising  from  overflow,  infiltra- 
tion, and  underpressure,  which  are  the  destruction  of  earth  or  masonry 
dams.  They  can  also  resist  the  earthquakes  as  was  proven  by  the  good 
conservation  of  the  California  Dams  of  this  type  even  after  the  violent 
earthquake  which  razed  to  the  ground  the  Gity  of  San  Francisco". 
(Giornale  del  Genio  Civile.  Civil  Bng.  Journal,  Jan,  31,  1917,  page  25) 
Or  again: - 

"For  the  Valleys  of  the  Alps  or  the  high  Apennines,  for  those  of 
Calabria  and  Sicily  subjected  to  seismic  shocks,  or  for  Lybia  -  where  there 
is  difficulty  of  transportation,  and  where  hand-labor  is  also  lacking,  the 
Rock  Fill  Dams  offer  a  more  simple,  rapid,  economical,  and  above  all,  a 
more  secure  construction,  even  in  the  cases  of  earthquakes,  and  are  for  this 
reason  worthy  of  the  faith  of  our  engineers.  They  are  especially  adaptable 
for  high  mountain  lakes;  and  in  fact,  as  already  stated,  the  Council  of 
Public  Works  in  its  meeting  of  December  30,  1916,  has  definitely  admitted 
it."  (Annali  Societa  Ingagneri  Italian!,  Mar.  1,  1918,  page  72.) 
Or  again: - 

"In  seismic  regions,  equally,  the  Rock  Dams  are  absolutely  to  be 
preferred  to  all  others,  as  much  for  their  easy  construction  as  for  their 
stability  under  all  circumstances.  And  it  is  to  this  type  of  Dam  that  the 


that  the  Italian  Engineers  will  do  well  to  aspire  in  projecting  Dams  in  the 
high  Apline  valleys,  and  above  all,,  in  the  Apennines  so  subjected  to  seismic 
movements,  abandoning  the  old  type  with  "gravity  section"  so  much  used  in 
the  past,  when  they  were  constructing  at  low  elevations,  but  too  inconvenient 
in  the  high  mountains,  rather  costly,  and  that  no  one  can  have  a  reason  for 
preferring  to  Rock  Dams".  (Annali  Societa  Ingegneri  Italiani,  I.iiir,  1,  1918, 
page  73. 

In  the  chronicles  of  the  technical  papers,  frequent  notices,  wnose 
author  is  not  mentioned,  mention  more  ambitious  projects  in  regard  to  Hock 
Dams.  These  finally  readh  otu*  office,  and,  with  clever,  inciting  arguments, 
fortify  the  statistical  claims  of  the  preceding  projects  and  warmly  praise 
this  type  of  Dam. 

She  more  recent  reference,  concerning  the  project  of  a  Rock  Dam  about 
75  meters  high  in  the  Apennine  Valley  of  Bnza,  is  considered  specially  for 
the  constructions  in  Calabria  and  Sicily. 

"On  account  of  the  seismic  movement,  the  Hock  Dams  are  the  only  ones 
advised,  as  experience  proves  in  several  instances  in  California, the 
classic  land  of  Rock  Dams  and  of  strong  seismic  shocks".  (Annali  Societa 
Ingegneri  Italiani,  June  16f  1918,  page  187. 


It  is  conceivable  that  the  recommendations,  so  constantly  urged  with, 
examples  of  the  absolute  prevalence  of  the  merits  of  the  Rock  type  Dam, 
for  its  applicability  in  the  Alps,  the  Apennines,  and  in  all  seismic 
countries,  etc.  whereger  the  mountain  dams  occur,  must  be  decided  by  more 
than  a  suggestion  submitted  to  cautious  criticism;  because  the  propaganda 
bears,  so  to  speak,  the  personality  of  a  brilliant  scholar,  a  high 
functionary  of  Civil  Engineering,  a  promoter  of  the  aforesaid  vote,  a 
member  of  the  Supreme  Adjudication  Board  where  things  are  judged  and  ordered. 

She  complex  suggestion,  which  it  is  not  necessary  to  analyze  here 


with  psychological  subtlety  in  its  diverse  factors,  is  also  favored  by 
other  tangible  arguments  handled  by  the  shrewd  practice  of  the  Projectors; 
the  manner  of  procedure  shortened  and  explained  by  most  pleasing  reasoning, 
the  doing-away-with,  or  at  least  the  greatly  modifying  of  many  old 
considerations  concerning  the  quality  of  the  natural  foundations,  the 
enormous  economy  that  follows  the  adoption  of  a  more  easy  construction.  In 
fact,  as  will  be  seen,  among  the  ;nany  merits  given,  there  is  the  one,  and 

it  would  be  of  real  worth,  tnat  the  Itock  Dams "do  not  need  to  be  placed 

on  compact  rock  as  is  indispensable  for  masonry  dams,  a  foundation  of  good 
clay  or  even  of  moraine  being  sufficient,  because  precautions  are  taken  by 
which  these  foundations  cannot  be  washed  away  or  eroded  in  any  way." 
((J.Q.C.  Jan.  31,  1917,  page  25.) 

On  account  of  tuis,  several  Administrations,  whether  of  the  Old  School 
or  the  Mew  School,  intested  in  the  search  for  mountain  locations,  are  agreed 
at  least  in  this  tenuency,  which  has  gone  beyond  the  incipient  stage,  of 
following  passively  in  the  projects  of  reservoirs,  the  smooth,  easy  way  of 
Bock  Bam  Construction,  Basy  way,  I  said,  and  so  it  is,  in  the  public  mind, 
even  though  the  Supreme  Water  Council  has  not  yet  pronounced  itself  in 
regard  to  this  matter,  having  held  for  many  months  and  still  holding  in 
reserve  its  course  of  action  concerning  Eock  Dams. 

In  fact,  the  admission  in  omy  one  case  (of  the  use  of  Rock  Dams)  should 
not  be  held  as  a  technical  victory  in  the  entire  Council,  any  more  than  the 
recent  incidental  passing  of  a  vote  (in  regard  to  the  same)  which  I 
learned  of  a  short  time  ago,  after  a  forced,  protracted  absence. 

Therefore,  the  passage  of  the  vote  above  referred  to,  according  to 
which  the  manner  of  construction  of  the  rock  dams,  "with  a  layer  of  eenant 
and  superior  asphalt-bitumen  on  the  side  toward  the  \vater,  corresponds  to 
the  rules  of  today  for  the  construction  at  those  altitudes  (Alpine  /alleys)", 
could  be  considered  as  a  most  important  decision  which,  in  my  opinion, 

cannot  be  discussed  except  in  a  se-oara.e  treatise1' 


This  refelction,  and  other  serious  motives  that  are  developed  from  the 
examining  of  the  recent  members  of  the  "Instruttorie",  and  above  all  the 
character  and  consistency  of  the  propaganda  in  favor  of  Rock  Dams,  caused 
me  to  aecide  to  talce  my  stand  against  the  current  tendency  of  the  day,  and 
to  express  my  deduction  obtained  through  laborious  meditation,  and  firmly 
opposed  to  the  exaltation  of  Rock  Dams. 

2.       Need  of  a  more  general,  independent  Study. 
Objects  of  these  investigations. 

On  the  other  hand,  the  Council  will  shortly,  through  sheer  necessity 
become  the  center  of  a  competent  and  special  investigation  concerning  the 
most  important  question  that  comes  witriin  its  scope,  that  of  the  High  Dams 
for  Reservoirs. 

I  say  a  "special  examination"  because  it  must  be  thoroughly  permeated 
with  the  truth  of  the  orohydrographic,  the  climatic,  the  demographic 

conditions  which  are  entirely  forgotten  in  the  easy  reference  to  divers 

f  . 
geographic  and  demographic  conditions. 

One  of  the  scopes  of  this  work  is  to  promote  an  important  official 
research  which  is  already  being  clamored  for  by  certain  authorities  that 
are  alarmed  (1,  page  30).  Other  reflections  (studies)  will  show  the 
values  of  tnis  plan. 

In  the  "Instruttorie"  to  vtfiich  I  alluded,  and  in  some  others 
(L.H.P.  numbers)  more  recent,  there  is,  on  the  one  hand  the  opposition  of 
the  Surveyors  of  the  Communes  lying  lie) low  the  places  for  proposed  high  dams, 
learned  Surveyors  opposed  to  Rock  Dams,  more  because  of  instinctive  3ack  of 
faith  than  on  account  of  reason  and  knowledge,  which  opposition  is  very 
real  even  if  it  is  weak;  on  the  other  hand,  there  are  opposed  to  these, 
the  Projectors  who,  in  the  face  of  observation  and  defense,  conclude  always 
with  the  argument  that  all  criticism  should  be  abolished. 

Omitting  the  greater  number  of  amplifications,  this  reasoning  is  held 


in  the  following  terras: 

"The  most  dependable  proof,  that  Rock  Dams  are  tnose  that  from  now  on 
present  the  best  requisites,  is  given  in  the  well-known  deliberations  of 
the  Supreme  Council  of  the  L.L.P.P.  that  advises  and  approves  them. 

It  is  sufficient  to  refer  to  the  writings  of  Prof.  Luiggi,  Chief 
Inspector  of  Civil  Engineering,  the  warmest  supporter  of  Bock  Fill  Dams, 
the  one  that  has  made  himself  their  apostle  after  profound  studies  on  the 
on  the  problem,  (probably  L.H.P.)  be  it  with  laborious  research  and  with  a 
visit  maae  by  him  to  America,  Australia,  Europe,  etc. 

Shere  follow  as  axioms,  tue  passages  I  nave  already  cited,  and  similar 
ones. 

Such  an  argument  is  regarded  as  a  guarantee  of  victory. 

Among  the  contenders  are  the  officials,  who  hava  in  hand  the  "Instruttori< 
and  are  evidently  placed  in  a  most  delicate  position  as  regards  the  freedom 
of  their  juogment,  for  we  must  admit,  the  project  of  High  Dams,  an 
entirely  new  one,  is  very  difficult  and  complex. 

5?hus,  for  example,  in  the  most  important  and  most  discussed,  recent 
"Instruttorie",  they  testify  in  accord  with  the  Projectors,  that  the 
presence  of  ice  in  the  frozen  Alpine  latces  will  have  no  influence  on  the 
Dams,  "because  this  will  evidently  not  augment  the  hydrostatic  pressure 
due  to  the  shut-in  water11. 

But,  aside  from  this  point  of  inherent  "ice-pressure",  there  are  others 
Of  grave  moment  debated  in  their  own  late  technical  publications,  and 
especially  in  American  publications:-  the  phenomena  of  under-pressure,  of 
the  transfusion  of  v/ater  in  time  under  slow  pressure  into  the  bodies  of  the 
Dams,  the  question  of  manimum  deflux,  etc.  all  of  which  need  an  adjournment 
for  in  reality,  it  is  difficult  to  know  definitely  about  a  live  subject  in 
process  of  evolution  and  to  treat  it  in  a  scholarly  way.  Tne  foreign  texts 
are  the  best  compiled  on  the  subject. 


This  is  stated  as  a  synthetic  impression  which  is  the  result  of  the 
examination  of  some  cases  given  in  the  "Instruttorie",  ana  which  proves  a 
present  need  for  serious,  general  study,  for  general  guidance  and  applica- 
tion. This  study  must  be  promoted  by  the  Council  with  the  collaboration 
of  some  technicians  and  specialists  on  the  subject. 

I  will  permit  myself  to  expound,  a  little  later,  a  proposition  that 
is  most  urgent  for  safety,  the  revision  of  the  flow  capacity  in  executive 
projects  for  Rock:  Dams,  it  being  imperative,  as  I  will  show  that  overflow 
in  a  rock-dam  means  most  probably  the  destruction  of  the  said  dam.  Thus 
the  complete,  arduous,  uncertain  estimate  of  a  unit  maximum  deflux  in 
certain  determined  basins  of  determined  area  remains  vitally  attached  to 
the  judgment  concerning  the  safety  of  Rock  Dams.  The  data,  that  I  see 
given  given  with  simple,  tranquil  presumption,  is  greatly  below  the  possible 
limits  of  maximum  deflux  in  the  Alpine  sections  to  which  the  Projectors 
allude.  Instead  of  adding  anything  new  to  the  theme,  the  "Instruttorie" 
refers  literally,  as  I  said,  to  the  "Scritti  Luiggi".  To  tnese  I  will 
exclusively  draw  your  attention. 

It  is  true  that  some  good  constructors  counseled  and  still  counsel 
the  building  or  dams  in  the  Alpine  valleys  that  are  not  in  fact  rock  fill 
dams,  as  they  are  said  to  be.   Their  structure  is  quite  different  in  every 
way,  being  of  dry  masonry.  It  is  true  also  that  the  pure  type  of  H0ck-Dam 
is  increasing,  at  least  on  the  chart  of  the  projectors,  to  the  most 
alarming  heights. 

Returning  therefore  to  the  "Scritti  Luiggi"  as  the  authoritative 
cause,  to  my  way  of  thinking,  of  the  mentioned  suggestions,  I  affirm,  {the 
proof  following),  that  the  first  place  accorded  to  Rock  Dams  does  not  have 
any  real  foundation  or  even  any  sufficiant  justification  in  the  divers  texts 
that  speak  on  the  subject  in  favor  of  the  propaganda.  Hot  even,  which  is 
more  serious  still,  is  there  any  justification  for  the  examination  of  the 


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technical  side  of  the  question  from  deductions  made  specially  from  American 
literature  and  the  application  of  said  rock  construction  in  America, 
therefore,  we  have  an  exaggerated  result  or  one  not  consistent,  which  gives 
rise  to  a  legitimate  repulsion  to  the  use  of  Rods  Dams  in  the  Italian  valleys. 

That  which  I  think  of  the  said  dams  and  their  too  exclusive  propaganda 
is  not  deducted  today,  but  has  been  known  for  more  that  a  year  by  some 
authorities  in  Rome,  Milan,  and  Turin,  and  moreover  it  is  known  to  the 
Honorable  Commandatore  Luiggi.  But  refuting  any  polemics,  and  having  hoped 
even  more  to  avoid  them,  I  will  say  that  the  work  I  have  undertaken  in  this 
paper  is  done  for  justifiable  motives  of  convenience,  because  of  my  position 
in  the  Council,  because  of  a  deference  felt  toward  a  benevolent  colleague, 
and  also  because  I  counted  on  the  spontaneous  reaction  or  discussion  of  the 
studied  technical  opinions.  This  hope  has  diminished,  and  because  nearly 
all  the  best  youth  of  cultured  mind  and  vigorous  mentality  are  found  in 
other  fields  not  less  worthy  of  them,  I  mast  the  debate  with  bitter  sincerity; 
I  also  meet  it  through  a  duty  now  indeclinable  seeing  the  part  that 
concerns  me  with  a  grave  collective  responsibility. 

I  feel  that  an  erroneous  information  given  today  will  facilitate  a 
result  that  would  quickly  have  dire  effects  on  the  Reservoirs  of  Italy 
that  are  a  most  important  factor  in  the  future  of  the  country • 

Another  very  necessary  point  in  these  notes  is  the  clarification  of 
all  the  given  data,  by  means  of  clear  speech  and  the  avoidance  of 
conventional  euphemisms. 


These  Notes  will  state  among  other  things: 

a.   That  the  technical  conduct  of  the  Scritti  of  the  Engineer  Luiggi,  on 
Rock  Dams,  on  account  of  a  lack  of  precise  references,  on  account  of  the 
inexactness  or  the  non-existence  of  too  many  facts  assorted,  on  account  of 
the  inexplainable  metamorphosis  of  numbersjand  dates  in  arguments  most 


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suggestive  ,of  a  favorable  propaganda,  leave,  in  whoever  is  in  a  measure  to 
analyze  things,  a  most  unfavorable  impression. 

b.  That  there  is  not  existing  required  specific  information  which  would 
make  of  the  Bock  Fill  Dams  the  only  ones  advisable  in  countries  subject  to 
seismic  movements  (as  are  said  to  be  the  only  ones  advisable  in  the  high 
Alpine  valleys).  The  earthquake  of  1906  in  California,  which  ruined 

San  Francisco,  did  not  ^ive  such  indications;  it  suggested  some  quite  contrary, 
which  give  rise,  as  a  result,  to  some  of  the  most  important  special  publi- 
cations on  the  disaster. 

c.  That  contrarily  to  what  can  be  remembered  from  the  said  "Scritti"  the 
Rock  Fill  Dams,  as  regards  the  U.  3.  of  America,  have  only  a  minimum 
frequency  of  application  in  the  entire  construction  of  High  Dams;  this  not 
only  as  regards  the  entire  U.  5.,  but  also  the  Western  States,  of  which 
California  is  a  small  part,  and  where  the  conditions  of  great  medium 
heights  of  the  basins  is  more  accentuated  than  in  California  itself. 

d.  In  the  same  Galif ornia,  the  type  of  Hock  Fill  Dam  never  prevailed, 
and  today  it  is  not,  as  we  are  led  to  believe,  recognized  to  a  point  of 
ideal  evolution,  but  is  in  a  state  of  decided  decline  for  High  Dams,  and 
one  can  say  almost,  that  new  examples  are  entirely  lacking,  wnile  the  Arch 
Dams,  the  Multiple  Arch  Dams,  the  Beinforceo.  Structures,  and  even  the 
depreciated  Gravity  Dam  (arched  base  or  not)  are  increasing  and  are  even 
taking  the  place  of  ruined  or  formerly-planned  rock-dams.  Imposing  gravity- 
dams  rise  at  most  high  elevations  in  the  immense  highlands  of  the  West. 

e.  That  the  flow  capacity,  capable  of  withstanding  efficaciously  all  the 
contigencies  of  overflow,  infiltration,  and  underpressure,  does  not  exist. 

f .  Another  point  as  regards  the  manner  of  breaking " The  midf ift 

on  the  upstream  side  will  be  liable  to  a  break  allowing  an  escape  of  the 
water  in  the  frreak  of  the  midrift  of  the  dam  will  not  be  able  to  flow  out 

at  one  surge  but  only  quite  slowly,  and  thus  those  disasters  that  occur 


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with  other  types  of  dams  will  not  happen.   (Or.Gr.C.  Jan*  31,  1917  page  26.) 
This  condition  does  not  exist,  because  with  the  overflow,  with  the  partial 
sediment,  or  with  the  breaking  of  the  thin  cemented  midrift,  come  new 
elements  of  extreme  violence,  always  factors  in  the  most  rapid  and  complete 
ruin. 

g.   That  the  comparisons  with  types  in  other  countries  must  not,  in  any 
case,  ever  forget  to  consider  the  geographic,  climatic  and  demographic 
conditions  inherent  to  the  place  of  application. 


The  United  States  is  an  immense  laboratory  for  constructive  experiments. 
Because  of  the  immense  vastness  of  its  orohydrographic  system  as  regards  the 
density  of  the  population,  it  can  stand  all  kinds  of  experiments* 

For  a  first  example: 

The  Colorado  River,  whose  basin  of  632,000  sq.  km.  is  2  -  1/4  times  the 
area  of  Italy,  interests  more  or  less  eight  states  of  the  west,  -  among 
which  are  Colorado,  Arizona  and  California,  with  plains  at  an  immense  height 
in  the  Rocky  fountains.  Tnis  section  had  a  population  of  457,000  inhabitants 
in  1915  (1)   But  the  conditions  change  with  vertiginous  rapidity,  and 
proceeding  by  means  of  the  given  analysis,  and  by  reason  of  a  profundity 
practical  and  scientific  sense,  they  enforce  a  curb  through  the  legislation 
which  becomes  more  and  more  severe  and  inflexible. 

At  one  time  there  were  literally  undertakings  or  constructions  which 
went  to  pieces  daily.  The  technical  journals,  so  as  not  to  reduce  their 
subject-matter  to  a  mere  chronicle  of  disasters,  declared  that  they  would 
omit  the  greater  part  and  limit  themselves  to  only  the  most  instructive 
cases.  The  construction  of  reservoirs  that  do  not  stand,  or  of  dams  that 
crumble,  is  not  hidden  under  a  cloak  of  silence  and  kept  from  public  notice 
until  accidentally  the  veil  is  raised, but.  is  immediately  brought  to  the 

aotice  of  the  public  with  a  sincerity  that  is  the  reason  and  cause  of  progress 


. 

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in  a  matter  which  is  not  stable,  and  in  the  limited  knowledge  tnat  we  have 
concerning  it. 

It  is  noticeable,  also,  that  in  France,  which  has  a  large  Alpine 
section,  and  in  Switzerland  which  is  entirely  situated  in  the  Alps,  there 
is  not  as  far  as  I  know  any  application  of  itock  tfill  Dams.  The  beginning 
of  a  propaganda  for  their  use  was  started  in  Switzerland  (by  ilng.  Klllias 
in  the  Schweiz  Wasserwertschaft  of  1912,  jtfos.  22  and  23,  consequently 
before  usj  and  was  not  followed  out.  jtfhe  projects,  as  far  as  I  know, 
though  many  are  very  daring,  contemplating  the  erection  at  great  heights  of 
beautiful  dams,  consider  either  the  Gravity  of  Arch-type  dams,  or  those 
known  as  the  Ambursen  type. 

These  nations  are  learned  with  traditions  that  Joave  been  carefully 
worked  out.  ihey  follow  the  American  technique,  at  least  as  much  air  we  do, 
but  these  nations  realized  instinctively  the  difference  in  the  possibilities 
of  experimental  constructions  in  their  territories,  which  differ  so  greatly 
in  size  and  conformation  from  those  of  the  U.  3. 

This  reason,  i  repeat,  is  one  of  innate  geographic,  demographic,  and 
climatic  conditions.  I  felt  this  reason  strongly  specially  in  viewing  the 
immense  collection  of  topographic  chatts,  and  in  looking  through  the 
volumes  of  the  U.  3.  G-eological  Survey,  and  the  .Reports  of  the  U.  S. 
Eeclarnation  Service,  i.  e.  the  reports  gathered  from  450  volumes  of  which 
I  possess  the  greater  part,  from  the  Water  Supply  Papers  of  tne  U.  3.  G.  S., 
a  complete  monography  of  geographic. and  hydraulic  descriptions  over  an 
immense  and  varied  territory,  more  tn&t  thirty  times  that  of  our  country, 
and  having  immense  general  orohydrograpnic  areas,  i'his  is  combined,  it  is 
understood,  with  a  study  of  the  density  of  the  population  ta«ceu  from  various 
censuses  of  several  states.  This  density  in  the  valleys  of  the  .Western  States 
is  still  often  the  hundredth  or  the  thousandth  part  of  that  in  our  populous 
little  valleys  which  will  be  interested  in  the  placing  of  reservoirs  insomuch 
as  they  affect  their  safety.  iNo.  2,  page  31 j. 


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In  these  Notes  and  in  other  places  in  the  discussion  of  iiock  tf 
Dams,  l  want  to  say  that  I  am  not  absolutely  adverse  to  the  Dams  themselves. 

According  to  ray  way  of  tninfcing,  they  could  "be  considered  favorably 
in  some  cases,  and  again  have  a  fatal  result  if  used  to  retain  water,  even 
in  a  moderate  amount,  in  some  of  our  little  valleys.  They  could  be  used 
provided  they  were  designed  with  extreme  care,  one  can  never  definitely 
state,  so  to  speak,  the  method  of  calculation,  and  above  all,  there  must 
be  allowed  a  great  latitude  in  providing  a.  flow  capacity. 

This  is  easy  to  state,  but  it  is  difficult  for  even  a  most  skillful 
constructor  to  calculate  correctly. 

My  decided  preference  for  the  general  construction  of  High  Dams  is  the 
Masonry  Dam;  —  A  Masonry  Dam  with  a  single  arch  or  with  multiple  arches 
according  to  the  form  of  the  gorge,  the  solidity  and  compactness  of  the 
surrounding  rocks  etc.  In  general,  I  prefer  the  Sravity  Dam,  with  an  arched 
base,  planned  after  careful  study  and  using  the  most  recent  precautions  as 
regards  specially  the  debated  subject  of  a  possible  under  pressure. 


3.       First  Conceptions  Concerning  the  Irregularity  of  the  Method 

Used  in  the  Propaganda Morena  Dam,  Strawberry  Dam, 

Gratun  Dam,  and  Lov/er  Otay  Dam. 

The  writings  of  Professor  Luigi  Lwiggi  are  generally  mentioned  in  the 
arguments,  I  will  for  brevity  designate  them  as  "Scritti  L.  L."  Passing 
over  the  minor  points  of  the  chronicle  and  of  the  Propaganda,  I  will  use 
others  as  I  need  them.  I  give  here  a  succession  of  numbers  in  conventional  use 

N  (1)  Nuova  tipo  di  Diga  Bconomica  per  Laglu  Artificiale:  Diga  della 
Biaschina,  (G-.G.C..,  January  1913,  riprodotto  con  altro  titolo 
negli  A.I.I.  May  1913. 

N  (2)  Evoluzione  delle  Grandi  Diglie  per  Laglu  Artificiale.  Conference 
published  in  the  "Industria"  No.  7  to  14  and  interpolated  in  1914 
in  the  "Atti  3.  Schenze  and  A.I.I.) 

N  (3)  Dighe  per  Laghi  Artificial!  recentemente  construite  in  Italia 
(G.&.C.  March  1917). 


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N  (4)  Dighe  di  Scogliera  per  Laglu  Artificial!  in  alta  montagna 
(G.G.C.  No.  January  31,  1917.) 

N  (5)  Diga  di  Scogliera  di  Strawberry  in  California,  (A.I.I.  Mar. 16,  1917) 

N  (6)  Per  L'utilizzazione  delle  Acque  en  alta  raontagna.  A  conference 
reproduced  in  the  A.I.I,  and  interpolated  into  the  July  Ho*  1917 
and  Mar.  No.  1918,  of  the  "Atti  S.  Acievoza.  I  also  will  refer  to 
the  "Bstratto". 

Particularly  interesting  for  our  work  because  it  is  more  technical 
and  keeps  more  to  the  theme,  is  the  "Scritto  N(4)"  of  the  Giornale  Del 
Genio  Civile,  Jan.  31,  1917  (1  and  page  30)  in  which  the  arguments  have 
already  assumed  a  definite  character* 

Considering  the  cnaracter  of  the  "Scritti  Luiggi",  it  would  suffice 
to  mention  them  without  submitting  them  to  severe  criticism.  Other  texts 
will  be  of  use  for  comparisons  in  the  case,  because  he  wno  now  wishes  to 
cunfute,  must  above  all  greatly  desire  in  him  who  listens  and  judges,  a 
direct  and  sufficient  knowledge  of  the  texts  which  serve  as  a  source  of 
information. 

In  this  section  are  stated  the  first  and  already  significant  proofs 
concerning  the  assertions  made  in  (a)  of  the  preceding  paragraph.  These  deal 
with  the  unfavorable  impression  that  is  immedately  made  on  the  reader.  In 
this  first  glance,  one  sees  the  characteristic  phases  of  the  "Scritti  L.L.'1 
exhibited  in  various  manners,  which  continue  all  through  his  Scritti.  'fixe 
scarcity  of  the  Sources  referred  to  shows  the  poor  ground  he  has  for  advocating 
the  adoption  of  notable  recent  nock  Fill  'x'ype  Dams*  I  will  prove  this  statemeni 

The  examples  concern  the  two  Immense  rock  dams  of  Morena  and 
Strawberry  in  California,  the  collosal  Gatun  Dam  of  the  Panama  Canal,  the 
Lower  ^tay  Rock  Fill  Dam  in  California  and  its  destruction. 


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dam  is  in  San  Diego  County,  Southern  California  and  holds  the 
laurels  for  its  daring  height  which  is  150  ft,  or  45.75  meters  and  not  61 
or  61.5  meters  as  the  works  of  L.  L.  (LuiggiJ  would  have  us  believe.  In 
reality  in  his  first  report  L.  (LuiggiJ  indicated  it  as  being  36  meters  high, 
but  in  his  second  report  and  in  all  the  following  ones  as  61  rnetors  or  61.5. 
A  recent  notice  in  a  chronicle  (A.  I.  I.  June  16,  1918)  with  data  concerning 
the  Dam  of  i*azza  in  the  Enza  had  called  attention  to  t  e  fact  the  the  Dam 
was  75  meters  high,  "being  the  highest  Rock  Fill  Dam  in  the  world  as  the  othor 
two  highest  similar  dams  of  the  korena  iiiver  and  the  Strawberry  in  California 
which  are  61  and  56  meters  respectively  are  far  greatly  surpassed  by  this 
aforesaid  one."  (A.  I.  1.  June  16,  1918,  page  187.)  The  two  highest 
American  are  in  reality  one,  45. 7o  meters  and  not  61  meters,  and  the  other 
42.70  meters  and  not  56  meters.  She  difference  in  the  height  is  great  enough. 

The  descriptive  account  written  by  the  constructing  engineer  O'Shaugh- 
nessy  about  the  Morena  Dam  in  the  "Transactions  of  the  A.3.C.E.,  1912, 
pages  27  to  62  to  which  Luiggi  refers  continually  ia  in  truth  the  only  vjork 
of  the  last  decade  in  the  classic  collections  of  the  P.C.E.  which  refers  to 
the  rock  dams,  while  those  referring  to  the  masonry  dams  of  various  types 
are  numerous.  The  Construct  or  explains  clearly  by  drawings  and  by  numoem 
in  the  text  that  the  Morena  Dam  is  150  f£.  high  ^boc.  cit.  pg.  35,  36,  37, 
41,  47  etc.) 

It  is  well  indicated  that  the  wall  of  simple  "talions"  on  top  of  the 
trapezium  of  rock  descends  112  ft*  (34.16  meters)  to  the  rock  under  the 

foundation  base,  from  which  the  constructor  counts  the  150  ft.  elevation 
(total  262  ft.  or  79.91  meters.) 

Therefore  when  the  constructor  himself  makes  an  estimate  on  the  cost 
of  a  supposed  masonfry  Dam  he  takes  logically  as  a  base  the  entire  height; 


but  there  is  no  legitimate  reason  for  counting  the  real  height  in  the  case 
of  a  itock  Dam.  According  to  its  Constructor,  the  Morena  Dam  is  150  ft. 
i.e.  45.75  meters. 

When  in  1916,  the  Morena  Dam  escaped  by  pure  luck,  (as  one  would  say, 
a  narrow  escape,  an  expression  which  is  equal  to  miraculous  escape)  the 
ruin  which  struck  the  Lower  Otay  hock  Dam,  the  experts  who  discussed  the 
circumstances  of  this  lucky  escape  of  the  Morena  Dam  and  urged  measures  that 
should  be  adopted  to  make  it  secure,  repeatedly  mention  its  height  at  IbO  ft. 
For  further  proof  see  "Eng.  .wews"  of  Dec.  14,  1916  on  the  plans  for 
ameliorating  the  Morena  Dam,  with  the  report  of  Cromwell  to  the  San  Diego 
Council,  also  the  "Eng.  Hecord"  of  tfeb.  12,  1916  on  the  breaking  of  the 
Lower  Otay  Dam  etc. 

But  this  assumption  of  a  height  of  61  meters  is  derived  from  an 
alteration  of  the  original  drawings  of  iJngineer  O'Shaughnessy  which  we  hold 
as  unjustifiable;  -  (page  36f  37)  copied  in  drawings  5,  6,  7  of  Plate  1 
(Jiornale  u.  Civile,  Scritto  MN"  (4)  and  also  numbers  33  &  35  in  Scritto  H  (6) 

The  line  which  the  constructor  of  the  Dam  calls  50  ft.  i.e.  15.25 
meters  under  the  base  of  support  (a  prop]  of  the  rock  construction  is  taken 
as  zero  in  the  works  of  L.L.  i'he  real  zero  elevation  then  becomes  15.25 
meters  and  the  top  of  the  Dam  elevation  45.75  meters  (150  ft.)  becomes  61 
meters.  And  thus  there  is  a  laborious  and  singular  new  quoting  of  all  the 
data  given  in  the  drawings  of  the  Engineer  O'Shaughnessy. 


Here  also  we  find  a  great  deviation  in  the  real  height  of  the  Dam. 

2ha  indication  in  Mote  N  (4)  page  13  seems  exact:  *  "The  dam  is  in  its 
entire  height  53.20  meters  of  which  10.50  m.  are  in  the  foundation  under 
the  bed  of  the  river  and  42.  70  meters  are  above,  'i'he  statement  leads  to 
a  singular  misconception  when  the  altitude  changes  from  42.70  meters  to  53 


meters  and  again  to  56  meters  in  more  recent  descriptions* 

The  midrift  diaphragm  that  continues  the  wall  and  rises  or  descends 
to  join  the  rock  is  included  in  the  height  which  thus  receives  a  great 
increase  not  really  existing.  u!he  same  structure  of  rock  dan  that  is  for 
example  10  meters  at  its  plane  of  support  would  be  20  meters  if  its  ret«in- 
ing  wall  joined  the  rock  10  meters  under  the  said  plane  of  aupport,  -  or 
40  meters  if  it  were  30  meters  under  -  while  it  is  eviaent  to  all  that  for 
the  statistical  considerations  of  the  rock  structure,  the  height  is 
considered  from  the  plane  of  support  and  not  differently. 

That  this  is  an  incorrect  and  arbitrary  way  of  calculating  the  height 
of  Hock  Liams  allowing  elastic  dilations,  is  proved  in  the  same  article  in 
the  "Eng.  Record"  of  August  26,  1916,  pages  260-262  from  which  Professor 
Luiggi  took  designs  and  text  prepared  expressly  fromUotes  N  (5)  of  the 
Strav/berry  Dam,  but  which  is  not  cited  in  the  "Works"  themselves  nor  in 
any  other  "writing". 

The  original  text,  besides  its  clear  drawings,  says  moreover:-  "He  is 
constructing  a  dam  of  rock  type  with  a  skin  of  masonry  having  an  impervious 
coating  on  the  mountain  side.  A  rock  dam  should  have  a  maximum  height  of 
140  ft*  above  the  bed  of  the  river  while  the  cut  off  wall  must  toe  carried 
to  a  depth  of  33  ft.  under  the  bed  of  the  river." 

But  there  is  another  disagreeable  circumstance  that  must  be  revealed. 
While  the  drawings  of  the  Strawberry  Dam  are  copied  from  the  original  in 
the  article  just  mentioned  (See  figures  8  and  9,  table  11  of  Luiggi *s 
"Scritto"  N.  5  figures  36  and  37  of  'Scritto"  N.  6  and  see  the  original 

drawings,  page  261  in  the  Eng.  Becord)  the  said  copies  are  retouched  by  the 
added  arbitrary  ledgos,  "shelves"  on  the  ground  floor  and  the  sections. 

These  ledges  and  a  few  other  added  particulars  on  the  floor  of  the 
valley  would  bring  the  Strawberry  Dam  nearer  to  the  type  proposed  by  L.L. 
in  the  "Scritto",  -  but  these  do  not  exist  in  the  original  drawings  or  in 
the  construction.  The  "paramento"  -  (retaining  wall)  to  the  valley  is  in 


one  unbroksn  line  at  an  angle  of  1.3  at  the  base  for  1  in  height. 

It  might  "be  supposed  that  these  additions  are  derived  from  special 
information  given  by  the  Directing  Engineer,  Howson;  but  without  stopping 
for  another  unpleasant  reaelation,  let  us  say  that  this  is  evidence  gained 
from  another  source,  -  not  the  article  of  "Eng.  Record"  the  only  one  tnat  is 
used  in  the  Scritto  L.  L.  N  (5)  on  the  Strawberry  Dam.  It  is  in  the  article 
of  the  same  i*.  Howson  under  whose  authority  the  work  of  the  Dam  was  executed 
(O'Shaughnesay  being  still  the  Consulting  Engineer)  which  appeared  five  month 
before  the  other  in  the  "Eng.  News"  March  30,  1916  p.  604,  where  the  great 
insistence  is  put  on  the  ledges,  and  they  are  clearly  outlined  in  the  drawing 
of  the  valley.  This  in  truth  does  not  concern  a  special  method.  As  the  type 
of  the  Morena  Dam  was  already  in  1913  the  "ideal  type",  (Scritto  L.L.  N(l) 
page  8)  the  type  of  the  Strawberry  Dam  is  a  more  recent  type  of  superlative 
perfection:-  "In  its  entirety  the  Strawberry  Dam  represents all  knowledge  that 
30  years  have  demonstrated  as  necessary  to  guarantee  in  an  absolute  manner, 
as  far  as  is  humanly  possible,  the  stability  of  tuia  construction  even  in 
seismic  regions  like  those  of  California:  at  the  same  time  reasonable  and 
admissible  in  practical  construction  as  far  as  expenses  and  time  are  necessar 
for  executing  the  work  are  concerned".  "And  the  Superior  Council  of  Public 
?/orks  conscious,  as  one  might  say,  -  of  the  importance  of  such  works" 
Scritto  L.  L.  H  (5)  A.  I.  I.  page  86  of  March  6,  1917. 

Now  we  must  eliminate  the  small  frequent  benches  of  3  meters  which  break 
the  wall  to  the  valley  at  irregular  intervals  in  the  Strawberry  Dam  and  in 
the  type  proposed  by  the  "Scritto11  L.L.  -  The  Morena  Dam  has  in  fact  only  one 
bench  of  6.45  meters  half  way  up  the  Dam,  made  according  to  the  most  modem 
models. 

The  reason  for  the  existence  of  these  benches  is  that  they  supposedly 
facilitated  the  construction  of  the  Dam  (Scritto  N  (4)  page  11)  which  is 
really  not  true:  but  for  security  we  prefer  in  every  case  a  single  line  - 
outward  .tangent  to  the  broken  surface. 


:'.*-. 

-      -  -    - 

! 

...  . 


- 


.:-„'. :.      . 


If  there  are  at  least  95  chances  out  of  100  that  a  Hock  Dam  be  subject 
to  destruction  when  it  is  subjected  for  a  few  hours  to  overflow  from  its 
highest  point,  -  we  claim  that  such  a  chance  is  augmented  when  the  even 
incline  is  broken  by  several  ledges. 

THE  GATUN  DAM  OF  PANAMA  iiADE  OF  EARTH  AHD  ROCK. 

Besides  the  two  darns  of  Morena  and  Strawberry,  greatest  on  account  of 
the  boldness  of  their  elevation,  there  is  another  wonderful  darn  which  is 
presented  to  the  world  as  a  Rock  Dam,  (Jatun,  the  darn  in  Panama  but  it  is 
not  a  rock  dam.  In  the  "Scritto"  L.  L.  N  (2)  the  darn  is  said  to  be  about  40 
meters  high  with  such  gentle  slopes  that  the  width  at  the  base  is  over  900 
meters  "formed  by  a  nucleus  of  rock  covered  with  clay.—  This  can  give  auu 
idea  of  the  faith  that  the  American  Engineers  have  in  the  "Rock  Dams"  •  since 
they  adopt  it  for  a  work  as  important  as  the  Panama  Canal;"  (loo.  cit.,  p.  9 
to  the  Estratto)  But  the  greatest  argument  by  which  he  persuades  us  to  give 
up  all  hesitation  is  here  outlined  (Scritto  Luiggi  H  (4). 

And  in  fact  the  North  Americans  wanting  to  construct  the  Gratun  Dam, 
which  is  perliaps  the  most  important  factor  in  the  functioning  of  the  Panama 
Canal  -  (which  will  be,  so  to  say,  eternal),  -  adopted,  as  one  can  see,  a 
rock  dam  filled  in  with  earth  as  the  only  one  safe  in  regions  subject  to 
seismic  disturbances."  (loc.  cit.  page  5)  -  and  again,  "The  (Jatun.  Dam  is  an 
enormous  mass  of  rocks  rendered  impermeable  by  means  of  clay,  by  reason  of 
its  dimensions,  «-nd  because  of  the  great  precautions  taken  so  that  it  can 
resist  all  possible  calamaties,  it  is  certainly  the  most  important  rock  dam 
yet  constructed." 

She  Dam  is  about  4o  meters  high,  with,  a  maximum  water  retaining  height 
of  31  meters.  It  thus  rises  9  meters  above  the  maximum  level  of  the  lake, 
*&is  avoiding  absolutely  the  possibility  of  overflow.  Tne  slope  is  most 
gradual,  at  the  top  5  in  base  for  1  in  atlitude  and  in  the  valley  a  base  of 
25  for  1  in  elevation.  The  fact,  that  after  many  years  of  mature  stuiy,  a 
Commission  composed  of  five  specialists  of  world  renown  adopted  a  dam  of 


. 


. 


. 
. 


19 


rock  foundation  is  the  proof  that  rock  dams  used  rationally  and  with  great 
foresight,  are  those  that  present  the  maximum  stability  under  most  violent 
shocks  such  as  Panama  is  subject  to",  (loc.  cit.  page  16,  17).  The  argument 
is  used  to  carry  decisions  but  it  is  not  possible  to  believe  the  ^atun  Dam 
a  rock  dam,  much  of  the  data  being  visibly  incorrect. 

The  article  of  ^egmann,  "The  Design  and  Construction  of  Dams",  in  the 
same  6th  edition  K.  Y.  1911  quoted  repeatedly  in  the  'Scritto  L.  L,f-  gives 
an  extensive  report  of  this  dam  with  drawings,  the  descriptions  of  which 
were  expressly  prepared  for  the  edition  of  March  1911.  This  text  cites 
Golonel  G'OQtnals  (now  Major  uen. )  as  the  Cnief  Engineer  and  President  of  the 
Panama  Canal  Commission  (p.  453  and  458).  The  work  of  Wegmann  should  be 
placed  in  every  School  of  Engineering. 

From  the  drawings  it  gives  and  from  the  subject  matter,  as  well  as  from 
more  recent  descriptions  given  in  1917,  one  gets  a  very  concise  idea  of  the 
height  of  the  dam.  Chief  among  these  later  reports  is  that  of  "The  Annaul 
Report  of  the  Isthmian  Commission".  These  all  point  out  that  the  height  of 
the  dam  is  115  ft.  (35»08  meters,  not  40  meters)  reducing  its  highest  point 
to  104  ft.  or  32  meters.  The  nighest  water  mark  is  85  ft.  (25.92  meters  and 
not  31),  the  width  at  the  base  is  2019  ft.  (615.79  meters  and  not  900)  etc. 
With  these  dimensions,  if  it  were  true,  as  the  "Scritto"  L.  L.  -  calls 
to  mind  (loc.  cit.  p.  17)  that  one  was  dealing  with  a  rock  frame-work  or 
"with  a  mass  of  rock  into  which  has  been  infiltrated  an  enormous  mass  of 
clay  by  means  of  hydraulic  sluicing"  -  the  example  given  would  make  one 
fearful  of  using  the  roak  dam  for  Reservoirs  -  be  it  on  account  of  the  great 
deviation  between  the  top  and  the  base  -  25  meters  of  retention  and  600 
meters  at  the  base  of  the  construction;  -  or  were  it  for  the  fact  that  the 
under  construction  -  the  real  construction  being  an  elevation  of  impervious 
moraine  -  is  not  that  of  rock  dams,  where  according  to  the  rule  so  much  is 
insisted  upon  in  the  "scritto"  Luiggi  -  the  body  of  the  Dam  is  made  exclusively 
of  rock".  (See  "Scritto11  N(4)  page  20. 


• 

. 

•  . 


; 


But  above  all  the  fundamental  fact  is  that  the  framework  of  rock  does 
not  exist  because  the  Gatun  Dam  is  a  dam  with  a  framework  of  earth* 

Wegmann  begins  his  chapter  (p.  451)  by  saying  "As  regards  the  Panama 
Canal,  the  ^atun  Dam  is  in  construction  an  earthen  dam  of  7500  ft,  in  length 
and  about  110  ft.  in  height."  From  the  long  report  of  Goethals,  Constructor 
of  the  Panama  Canal,  in  March  1911,  the  following  extracts  will  suffice. 
"The  drawings  192  and  193  show  the  location,  the  project  and  the  outline 
adopted.  The  dam  will  be  an  earthen  dyke  7,700  feet  long,  390  ft.  wide  with 
the  normal  water  line  at  an  elevation  of  85  feet,  high  water  line  at  100  ft.; 
the  highest  point  of  elevation  reaching  115  ft.  and  the  base  at  the  section 
2019  ft.  wide  (at  sea  level).  The  dam  will  consist  of  hydraulic  fill  between 
two  toes  of  select  rock  1200  ft.  apart. 

The  hydraulic  fill  consists  of  clay  and  sand  brought  from  the  surroimdini 
country.  Four  suction  dredges  with  20  inch  tubes  distribute  the  filling  etc. 

In  figure  193  Wegmann  gives  every  detail  of  the  construction  of  the 
section  and  shows  that  the  rock  is  only  a  small  part  of  the  total  volume, 
and  not  the  main  framework  as  we  are  led  to  believe. 

If  the  &atun  Dam  was  in  Feb.  1911  about  2/3  of  the  work  then  being  done, 
(according  to  (ioethals1  report)  it  is  well  for  us  to  follow  the  s-aid  work  in 
the  "Annual  iteport  of  the  Isthmian  Canal  Commission"  reporduced  largely  in 
the  greater  part  of  the  technical  Periodicals:- 

Eng.  Mews  i.ov.  21,  1912  page  941 
»  *  Dec.  4,  1913  "  1123 
»  *»  Mov..  26,  1914  "  1093 

The  report  of  1912  is  particularly  interesting  for  the  analysis  of  the 
variations  and  changes,  sometimes  serious,  of  this  great  work  which  went 
through  many  modifications  until  at  last  the  character  of  the  earth  dam 
became  fixed.  "The  reductions  in  height  from  135  ft.  to  115  ft.  was  decided 
in  1909  immediately  after  the  displacement  of  the  rock  fill  that  occurred  at 
the  south  toe  of  the  Dam.  Another  lowering  of  the  altitude  from  115  ft.  to 
105  ft.  is  shown  in  the  Reports  of  1912  and  1913.  In  the  most  recent  technics 


descriptions  on  hand,  those  of  H.  Gretlow  (#1  p.  134)  the  earth  dam  is  105 
ft.  high  (32.02  meters)  and  is  exposed  to  a  maximum  water  level  of  from  85 
to  87  ft.  (about  26  meters)  at  which  level  the  dam  is  still  390  ft.  wide 
(119  meters). 

The  character  of  the  earth  dam  is  reconfirmed  (restated)  at  every  turn. 
"The  dam  is  an  earthen  embankment  of  7700  ft.  etc.  The  interior  construct inn 
is  formed  by  a  mixture  of  sand  and  clay,  dragged  in  by  hydraulic  process. 
The  entire  dam  contains  21  million  cubic  yards  of  material,  (about  16 
million  cubic  meters). 

The  dam  therefore  is  of  earth  because  it  could  be  of  nothing  but  earth, 
and  not  of  masonry  in  a  place  having  its  base  at  sea- level,  and  with  the 
earth  available  to  a  great  depth:  one  can  examine  the  accounts  of  the  same 
sections  of  the  ground  in  the  G-oethals  Report  as  in  the  Wegmanns.  Text  - 
page  452. 

This  being  fixed,  and  overlooking  the  details  of  secondary  importance, 
if  one  re-reads  the  passages  in  the  "Scritto"  L.  ^.  on  the  G-atun  Dam,  which 
make  it  the  perfect  prototype  of  the  Rock  Dam,  -  one  gets  a  most  peculiar 
impression,-  especially  when  one  realizes  that  the  distinguished  Author 
is  in  full  possession  of  the  English  language. 

The  writer  on  the  other  hand  has  a  mediocre  knowledge  (#2-  page  134) 
of  the  language,-  but  a  sufficient  one  to  understand  with  fair  accuracy 
what  is  said;  where  the  sense  is  more  obscure  as  it  is  in  a  literature  as 
full  of  idiomatic  expression  as  the  American,  -  a  capable  assistant  clears 
the  meaning. 

THE  LOvVER  OTAY  ROCK  HAM  RECENTLY  DESTROYED. 

The  recent  destruction  of  the  Lower  Otay  Rock  Dam  located  on  Dulzura 
Creek,  in  the  same  region  of  San  Diego,  Southern  California  as  the  ^orena, 
has  given  rise  to  an  important  number  of  analyses  on  Rock  Dams. 

The  analysis  of  certain  disastrous  causes  (Bouzey  and  Austin  above  all) 
are  without  doubt  the  best  factors  toward  progress:  at  least  for  the  types 


. 


.-.evo  Li. 


whose  vitality  was  worthy  of  a  real  and  permanent  conservation. 

In  this  case  the  analyses  above  cited  tolled  the  funeral  Imell  for  a 
type  never  suitable  even  in  the  u.  ij.  and  that  never  had  any  great  impor- 
tance for  frequency  of  application. 

As  for  the  great  value  of  the  alluued-to  discussions  in  the  problem 
of  the  Rook  Dams  we  will  return  to  it  in  a  later  paragraph.  On  the  same 
subject  the  "Scritto"  L.L.  -  give  divers  indications  all  erroneous  and 
equivocal  referring  "for  most  important  notes  to  the  "Eng.  Hews"  of  New  York 
of  Oct.  15,  1916,  where  are  described  minutely  the  causes  of  tne  disaster" 
(Scritto  L.L.  M  (4)  page  9). 

Shis  number  of  Oct.  15,  1916  of  the  "Eng.  Hews11  does  not  exist;  the 
numbers  having  the  fullest  descriptions,  the  analyses  and  arguments  are: 

Engineering  i-Jews  *'eb.  3,  1916  page  263 

"  M      "  10,  1916  '•  283 

"  "      •*  17,  1916  "  334 

H  "  Mar.  9,  1916  "  462  -  473 

"  "  Apr.  13,  1916  "  717 

»  "  May  25,  1916  »  1007 

»  "  Aug.  3,  1916  *»  231 

11  "  £>ec.  14,  1916  '»  1112 

11  fiecord  Feb.  12,  1916  "  225 

"  "  June  10,  1916  »  769 

"  *  Aug.  12,  1916  "  195 

Even  a  superficial  .knowledge  of  the  complete  decisive  arguments  in  the 
Atti  1912,  American  Soc.  Uiv.  Engineers,  to  which  the  "Scritti  L«L«" 
continually  refers,  would  have  avoided  an  exposition  of  the  facts,  -  such  is 
the  statement  of  the  Scritto  N  (4)  Gior.  Genio  Civ.  number  of  Jan.  3},  1917 
pages  8,  9,  21. 

2he  Dam  of  Lower  Otay  in  the  Scritto  L.  i,.  INI  (1)  page  7  of  the  Estratto, 
is  cited  as  a  model  of  its  type: 

Other  types  rational  enough  and  acceptable,  -  to  wit,  -  that  of  the  Lowei 
Otay  Bam  in  California,  made  simply  of  roclcs  thrown  together"  ....  became 
afterwards  the  disaster  laden  with  faults. 
(A)  Above  all  its  length  of  service  is  almost  doubled. 

"It  was  constructed  In  1887".   ( Scritto  L.L.  1^(4}  page  8). 


,    , 


! 


; 

.     : .       • 


"The  Lower  Otay  Dam  in  which  af tar  more  than  35  years  of  service"  - — 
(Scritto  i*  14  j  page  21  )• 

"In  every  way  this  one  had  given  good  service  for  many  years  wnen 
things  occurred  that  completely  destroyed  the  capital  invested  in  it, 
and  it  was  rendered  possible  to  re-erect  it  at  that  time  because  it 
demanded  a  small  initial  expense,  while  they  would  not  have  had 
sufficient  funds  to  rebuild  it  had  any  other  type  been  adopted". - 
(Scritto  N  (4^  page  21)  (foot  note). 

Now  talcing  information  from  other  sources,  -  the  Beport  of 
O'Shaughnessy  in  the  said  Document  Am.  Soc.  Civ.  Bng,  1912  specifies 
that  1887  sees  its  beginning  as  a  Masonry  Dam,  that  the  minds  of  the 
owners  alarmed  at  the  cost  changed  the  type  of  construction  and  that 
the  Rock  Dam  was  begun  in  1894  and  finished  Aug.  18,  1897.  The  height 
is  given  as  130  ft*  and  in  the  highest  section  a  maximum  of  134  ft. 
(40.87  meters). 

Therefore  it  was  in  existence  less  than  19  years  and  not  more  than 
35  yrs*  These  facts  were  brought  out  in  number  and  in  writings  in  the 
discussions  that  took  place  after  the  destruction  of  Jan.  27,  1916,  - 
so  that  even  at  a  glance  such  a  mistake  should  be  impossible.  (See 
Eng.  News  Feb.  10,  1916  page  283  -  Eng.  News,  Mar.  9,  1916,  page  462  - 
Notes  by  Sellew  etc. ) 

The  break  that  destroyed  the  valley  caused  an  enormous  amount  of 
material  damage  and  the  loss  of  only  14  lives  because  an  intelligent 
official,  the  Coroner  of  San  Diego,  had  the  order  given  to  leave  the 
Valley  when  the  level  of  the  water  was  still  4  1/2  ft.  (about  1.35  meters) 
below  the  top  of  the  Dam,  the  peril  attendant  upon  an  overflow  toeing 
dreaded.  The  few  victims  owed  their  misfortune  to  their  own  imprudence. 

Anyway  this  singular  judgment  upon  the  length  of  the  durability  of 
the  dam  was  not  accepted  even  in  the  County  of  San  Diego  which  is 
relatively  thinly  populated,  for  they  have  decided  to  construct  a  strong 


-.' 


, 


: 


gravity  dam  in  place  of  the  destroyed  rook  dam. 

(B)  My  allusion  to  the  type  of  reconstruction  contradicts  therefore  another 
assertion  of  the  "Scritto  L.L.  N  (4)  "after  more  than  35  yrs.  of  service 
the  midrift  deteriorated  so  much  that  in  the  last  year  the  water  escaped 
from  it,  and  now  they  think  of  replacing  the  old  Dam  by  another  more 
lasting  with  a  midrift  of  reinforced  concrete  placed  higher  up  on  the 
slope1*,  (loc.  cit.  page  21) 

Let  us  turn  again  to  the  occurrence,  -  the  escape  of  the  water  is  an 
excessive  attenuation  of  the  cause  of  the  destruction  of  the  Dam  which 
in  a  few  moments  opened  outwards  like  a  pair  of  gates  after  a  few 
inches  of  overflow  throwing  into  the  valley  an  enormous  wall  of  water 
that  covered  the  first  16  kilometers  in  48  minutes.  (Silent,  Bng.  News, 
Feb.  17,  1916  page  335). 

Onus  it  is  said  by  all  who  describe  this  that  the  Lower  Otay  Dam  was 
swept  out,  and  not  "that  the  water  escaped  nor  a  crevice  from  which 
grave  dangers  resulted  as  well  as  few  victims  in  the  valley  below" 
(Scritto  ft  (4)  page  9). 

But  the  most  singular  statement  is  that  another  rock  dam  is  to  be 
constructed  with  its  midrift  on  the  side  of  the  mountain.  One  can  find 
no  trace  of  this  in  any  of  the  American  technical  periodicals.  Any 
one  who  follows  them  will  find  immediately  that  tne  Lower  Otay  is  to  be 
reconstructed  in  masonry,  of  gravity  type  with  an  arched  base. 

0}he"Eng.  News"  of  Aug.  3,  1916  and  the  Bng.  Record  of  Aug.  12,  1916 
give  ample  notes  on  this  very  important  matter. 

In  regard  to  the  Lov/er  Otay  and  Barrett  Dams  in  the  same  section  as 
the  Morena  Dam  (Cottonwood  Creek)  in  upper  San  Diego  Co.,  the  already 
well-known  Constructor  of  the  Morena  and  Strawberry  Dams  Engineer 
O'Shaughnessy,  who  was  .a  warm  supporter  of  Rftck  Dams  till  1916.  submit  ted 
to  the  San  Diego  Council  two  proposed  "Gravity  Darns  with  arched  bases  in 
cyclopean  concrete"  -  which  were  accepted  after  the  first  hearing  on 


, 


- 


; 


July  17,  1916.  See  Eng.  Record  of  Aug.  9,  1917  page  285,  Oct.  4,  1917 
page  669,  which  give  the  details  of  the  contract  for  the  new  Lower  Otay 
Masonry  (rr^vity  Dam,  which  was  immediately  begun, 

These  facts  are  also  cited  on  account  of  tneir  evident  intrinsic 
importance. 

The  slope  of  the  sides  are  not  1:1  (loc.  cit.  page  8).  Already  in 
the  special  report  of  O'Shaughnessy  in  1912  it  was  indicated  that  they 
would  be  slightly  more  precipitous  1  1/2  horizontal  for  1  vertical 
(Report  cit.  page  30)  but  if  there  is  in  the  discussion  which  follows 
any  inexactness  it  will  appear  several  times  that  the  slopes  are  at 
least  1  1/4:1  (See  Cromwell ' sReport  -  Eng.  Hews  4pr.  13,  1916  - 
Cromwell  being  the  Engineer  of  the  city  of  San  Diego). 

The  assertion  then  that  "Nevertheless  the  Dam  gave  good  service  and 
possibly  would  still  be  rendering  good  service  if  an  exceptional  cloud- 
burst had  not  occurred  during  tfce  last  Autumn,  the  lake  being  full  and 
there  being  an  insufficient  overflow  area.'*  ..  (Scritto  L.L.N  (4)  Page  8) 

He  has  contradicted  all  the  well-known  data  that  is  found  in  every 
account  of  the  event. 

Above  all  in  the  report  of  Q'Shaughnessy  in  1912  it  was  revealed  that 
the  edge  of  the  overflow  in  the  Dam  was  at  an  elevation  of  124  ft. 
(37.82  meters)  and  that  the  Dam  had  never  been  subjected  to  such  a 
strain  as  being  so  completely  filled.  The  highest  water  level  in  1909 
of  119  1/2  ft.  leaving  at  such"  a  time  a  large  margin  to  the  overflow  rim. 

The  note  on  page  283  of  the  10th  of  Feb.  1916  Mition  of  the  Eng. 
News  says  again:-  "It  is  considered  that  in  the  19  years  since  the 
construction  of  the  Dam,  the  reservoir  was  filled  to  its  absolute 
limit  by  the  hurricane  of  last  month  that  destroyed  it." 

In  the  minute  description  of  the  Eng.  Record,  jb'eb.  12,  1916,  the 
overflow  level  seems  to  be  identified  with  122.8  feet.  The  comimg  of 
the  meteor  is  described  in  connection  with  the  rise  of  the  lake.  In  48 


,   . 

- 


,   .    x 


A 
8MJ08 


hours  from  the  15th  to  the  17th  of  Jan,  1916  the  lake  rose  17  ft. 
reaching:  on  Jan.  17th,  the  elevation  of  101  ft, 

Q?he  cloudburst  therefore,  did  not  find  the  lake  full,  "but  on  the 
contrary  17  &  22  or  39  ft.  (thereabouts)  about  12  meters  under  the 
level  of  the  overflow.  This  level  (122.8  ft.)  was  reached  on  Jan.  21st, 

The  break  came  at  4:45  P.M.  on  the  27th  with  the  water  level  of 
130.8  ft.  according  to  the  time  measure  adopted  in  the  aforesaid  report 
there  being  an  overflow  of  from  4  to  6  inches  above  the  crest  of  the 
Dam,  or"  from  10  to  15  centimeters. 

In  this  paragraph  we  believe  we  have  given  an  accurate  conception 
of  the  intrinsic  conduct  and  method  of  the  "Scritto  L.L."  in  examining 
some  of  the  arguments  that  have  great  value  in  the  propaganda. 

Anyway  the  non-exaggeration  of  facts  contained  almost  entirely  in  the 
Special  scritti  of  Technical  Character  N  (4)  of  the  0.  dal  a.  Civile 
Jan.  31,  1917  where  similar  analyses  are  reported  will  uphold  me. 

Now  I  come  to  the  intrinsic  value  of  the  arguments  for  or  against  the 
Rock-type  Dam  according  to  the  outline  traced  at  the  end  of  paragraph  2 
of  this  work.  This  valuation  is  deducted  from  an  analysis  of  the 
technical  American  Sources  procured  from  the  illustrated  twxt  method 
specially  disagreeable  conclusions  will  be  drawn  by  the  examination  of 
the  "Report  of  the  Defense  of  the  xtock  Types"  in  the  Istruttaria  dis- 
cussed by  some  well-meaning  projectors  from  whom  one  must  exact,  if  not 
official  authority,  at  least -an  accurate  knowledge  of  the  subject  under 
discussion.  Instead  of  this,  we  find  repeated  the  same  errors  of 
numbers  and  of  facts  as  in  the  "Scritti  L.L.11  Other  errors  are  added 
to  these  showing  definitely  that  these  reports  were  prepared  second- 
handedly,  an  act  that  is  intolerable  in  official  transactions  where  the 
public  safety  is  at  stake,  and  where  there  is  an  enormous  responsibility 
undertaken. 

I  will  not  enter  now  more  into  detail  concerning  this  matter  unless 


:  •  •  .          '       •  .  .  .       '  .  . 

•  •    .          .  .  :  •  . 


, 


.1!     . 


. 

.  .  .          •         . 


an  absolute  necessity  for  doing  so  cibmes  up. 

4.   -jjhe  Rock  i/am  in  Halation  to  Earthquakes. 

Erroneous  assertions  auout  the  San  Francisco  Earthquake. 
Essential  difference  between  Hock  and  Earth  Dams. 

Valuable  information  unfavorable  to  this  type  as  far  as  Earthquakes 
are  concerned. 

This  paragraph  assume  the  task  of  removing  an  illusion  concerning 
the  specific  requisite  advantage  of  the  Hock  Bam  — -  an  advantage  very 
precious  and  attractive  b|rt  which  does  not  now  exist. 

rJhe  illusion  touches  specially  our  lands  at  Galabfcia  -  Sicily  etc. 
afflicted  by  earth-quakes;  such  illusions  based  on  the  faith  in  the  "Scritti 
L.  L»";  these  illusions  are  looked  upon  as  current  axions,  -  but  the  hasty 
credulity  of  the  people.^  or  their  passive  deference  to  the  opinions  of  tue 
author,  are  freighted  with  perilous  results. 

Ihe  "Scritti  L.  L."  says  "The  Hock  Dams  are  the  most  secure  against 
all  calamities  even  earthquakes;  and  in  fact  all  the  Rock  dams  constructed 
v/ith  sufficient  slope  and  with  necessary  precaution,  resisted,  as  experience 
showed,  the  most  violent  shocks  of  the  3.  F.  earthquake,  ("Scritto  N  (4) 
page  5. )  A  mass  of  rocks  cannot  suffer  any  appreciable  damage  even  from 
the  most  violent  earthquake  snocks.  It  may  become  a  little  affected,  it 
may  undergo  a  si  nking,  but  it  will  not  be  disintegrated,  and  still  less 
will  it  cave  in,  or  be  wrenched  apart  ....  3)his  explains  how  the  indicated 
precautions  having  been  followed,  there  resulted  constructions  that  resisted 
the  violent  shocks  of  trie  most  serious  S.  F.  earthquake  (Scritto  M  (4) 
page  24)  ...  finally  they  can  resist  earthquake  shocks  as  was  well  proved  by 
the  excellent  preservation  of  the  California  Dams  of  this  type  even  after 
the  violent  earthquake  that  razed  the  City  of  San  Francisco  to  the  ground 
"Scritto  iM  (4)  page  25). 

A  statement  copied  word  for  word  from  the  Scritto  L.  L.  H  (4) 
with  the  following  note  as  an  ultimate  conclusion  in  the  most  recent  number 
of  the  "Annali  Ingegneri  Italian!"  of  March  1,  1918,  (Soritto  H  page  72.) 


' 


"For  the  Alpine  Valleys,  or  those  of  the  high  Appenines,  for  Calabria, 
Sicily  or  Libia,  subject  to  seismic  shocks  ...  the  Rock  Dams  oc'fer  the  most 
simple,  and  the  most  rapid,  the  most  economical,  and  above  all,  the  most 
secure  solution  even  in  case  of  earthquakes"  ...• 

The  assertion  and  the  reference  to  3.  F.  as  proof  have  an  undeniably 
resolute  precise  sound;  one  would  look,  however,  in  vain  for  any  definite 
source  of  information  in  the  "Scritti  L.  L.  ",  (1)  Already  when  about  a 
year  and  a  half  ago,  I  began  to  have  some  doubts  about  the  general 
reliability  of  the  "Scritti  L.  L.",  I  wanted  to  examine  more  deeply  the 
arguments  that  I  followed  at  first  as  contiguous  with  others  dealing  with 
my  favorite  occupation.  But  I  did  not  find  any  record  in  my  papers  correlate 
the  California  earthquake  with  the  Hock  Dams. 

I  had  read  also  at  the  time  the  Article  by  the  California  Jingineer 
O'Shaughnessy  on  the  Morena  Dam  in  the  Documents  A.  3.  C,E.  1912  to  which 
the"3critti  L.  L."  continually  refer,  but  in  this  I  did  not  see  a  thing 
about  such  a  correlation,  not  even  on  the  value  of  the  Rock  Dams  in  seismic 
zones;  which  great  value  should  have  had  the  3.  F.  Engineer  G'Shaugnnessy 
resumes  on  page  67  of  the  Paper  cited  in  favor  of  the  Rock  Dams.  #2 

IBims  in  the  volpminoiur  Wegmann  text  on  Bams  (1911),  the  American  text 
par  excellence,  in  the  few  pages  dedicated  to  the  Bock  Dams  (14  in  number 
the  same  as  for  the  timber  or  crib  Dams)  there  is  not  a  word  about  the 
essential  prerequisite  of  Kock  Dams  in  relation  to  earthquakes  and  still 
less  about  their  definite  result  in  the  3.  *'.  Earthquake  of  1906  so  clearly 
defined  by  the  "Scritti  L.  L."  The  same  can  be  said  of  other  sources  of 
information  still  raore  general  that  I  have  examined. 

It  is  understood  that  one  may  express  a  personal  opinion  as  to  how  a 
Rock  dam  would  stand  in  the  event  of  a  generic  earthquake.  Thus  easily 
with  no  effort,  1  have  found  a  former  writing  of  the  same  Engineer 
O'Shaughnessy,  Constructor  of  a  good  Hock  Dam,  who  took  part  in  1914  in  the 
"Discussion  on  Wall  and  Arch  Darns  for  Huacal,  liexico  the  Constructing 


".     . 


..... 


Engineer  being  Hawgood  —  in  the  "Proceedings  ,1.  .3.  G.  E.  Aug.  1914  page  E031. 
O'Shaughnessy  alluding  to  the  menace  of  earthquakes,  makes  tnis  remark  which 
does  not  exist  in  the  G'Shaughnessy  report  of  1912;-  "In  the  case  of  the 
Upper  Otay  Dam,  with  a  capacity  of  1,000,000,000  gallons,  situated  right  above 
the  Lower  Otay  Dam  and  above  the  reservoir  having  a  capacity  of  13,000,000,000 
gallons,  the  writer  was  always  worried  about  what  the  results  would  be  to  the 
Lower  Dam  if  the  Upper  Dam  were  to  break  through  an  earthquake  shock". #3 

This  Happened  in  1914.  As  has  been  said,  when  the  cloud-bufcst  of 
January  1916  left  unharmed  the  Upper  Otay  overflowing  by  over  90  centimeters 
of  welter,  ruined  the  Lower  Hock  dam,  the  same  O'Shaughnessy  put  an  end  to  all 
arguments  of  earthquake  possibilities  and  decided  to  recommend  for  the  Lower 
Otay  a  fine  Masonry  Gravity  Dam  which  is  already  in  course  of  construction 
in  Southern  California. 

There  have  been  other  various  personal  opinions,  justifiable  because 
ed 
foundAon  contradictory  statements,  -  or  because  rock  dams  were  mistaken 

» 

for  earth  dams:  but  the  fact  remains  of  the  proof  of  the  disastrous  earth- 
quake of  1906  which  should,  undoubtedly  nave  left  some  trace,  to  prove  its 
decisive  importance,  in  the  American  sources  of  information  already  mentioned, 
while  such  a  trace  does  not  exist  at  all. 

It  seemed  to  me  evident  that  any  conclusion  in  favor  of  one  kind  of 
dam  or  other,  in  regard  to  the  value  of  such  dams  from  an  earthquake  stand- 
point, should  be  the  result  of  examples  drawn  from  conditions  homogeneous 
enough  in  character,  as  far  as  earthquakes  are  concerned,  to  give  grounds 
for  the  deducted  results.  I  remembered  in  general  that  the  disaster  of 
April  18,  1906,  had  expended  its  greatest  intensity  in  Central  California 
and  specially  in  the  Coast  Hegion  where  are  found  established  several  artifi- 
cial lakes  with  notable  nigh  retaining  walls.  With  a  first-hand  examination 
of  the  great  amount  of  material,  and  facts  chronicled,  whose  discussions 
occupied  for  a  long  time  the  two  largest  technical  periodicals  of  the  u.  S.f  - 
the  Engineering  i^ews  and  the  Engineering  Hecord  after  April  18,  1906,  1  have 


• 


" 

.     ......••.:  ]         .: 

•  , 

.'.....  , 

..••—..         ,  - .     • 

;  •-   .  .,..•..-          ..  ,  .  s  ,  " 

•    . 

•     .  ....         ..          .  .     .  • 

« 
.  ...  .... 

•     •  '  :  •      •.      ' 


•    --... 
- 

(       •  .    .  .     '          •        .  -  ;  .     __  .       •  ; 

-  '  .  ...... 


not  succeeded  in  finding  any  sign  of  a  break  in  the  dams  of  the  artificial 
lakes. 

I  found  a  special  Heport  in  the  Engineering  lews  of  May  17,  1906, 
page  548:- 

"Some  effects  of  the  San  Francisco  Earthquake  on  the  Water  plants  and 
systems  etc.  by  the  Engineer  Professors  Grilman,  Hyde,  and  Derleth,  repre- 
sentatives of  the  Dept.  of  Civil  Engineering  of  the  U.  C,..rt  who  recount 
the  successful  resistance  of  two  large  dams  one  of  earth,  (San  Mateo  Dam), 
the  other  of  prismic  cement  masonry  dam  (Crystal  Spring  Dam)  in  the 
peninsula  of  San  mateo  just  south  of  S.  i'.  terribly  tried  by  the  accident. -- 
10°  on  the  itossi-tforrel  scale. 

Notice  the  Earth  Dams.  I  will  say  that  despite  their  withstanding  the 
shock,  tney  should  not  be  built  in  eartnquake  centers  any  more  than  the  Hock 
Dams,  i'here  is  not  a  word  in  the  neport  about  itock  Dams,  or  in  any  of  the 
chronicles  of  the  Earthquake.  I  found  other  d&cuments  more  general  in  nature 
and  more  descriptive  as  to  the  effects  of  the  Earthquake  of  April  18,  1906 
on  California  and  the  surrounding  regions. 

une  is  an  important  work  inserted  in  the  "transactions  of  the  A.S.C.E., 
Dec.  1907,  a  work  of  129  pages  and  36  plates.  "The  Effects  of  the  S.  *'. 
Earthquake  of  April  18,  1906  on  the  Engineering  Constructions".   It  is  the 
report  of  a  u-eneral  Committee  and  of  six  special  Committees  of  the  Association 
of  Members  of  the  S.  *'.  Section  of  the  A.S.C.E." 

In  report  C  (page  245)  of  the 'Committee  for  the  effect  of  earthquakes  on 
Water  Works  has  taken  as  example  in  the  damaged  region  the  Earth  and  Masonry 
Dams  for  artificial  lakes  as  well  as  other  Water  works  such  as  Distributing 
Towers,  1'ubation,  etc.  that  are  not  interesting  at  this  time. 

uf  Kock  Dams  there  is  not  a  word.  Evidently  they  do  not  exist  in  that 
part  of  California  most  exposed  to  earthquakes  or  else  they  are  not 
considered  worth  mentioning. 

Another  significant  point  that  does  not  precisely  uphold  the  assertion 


• 


31 


of  the  general  use  of  iiock  Jjams  in  California  is  commented  upon  in  the 
next  paragraph. 

'i'he  Special  iieport  G  conludes  about  the  jams  with  two  points,  2  and  3 
in  relation  to  water  Works  that  i  give  here  with  the  first  of  a  general 
nature,   iloc.  cit.  page  254-5), 

1.  in  future  greater  attention  must  be  given  to  placing  important  ¥/ater 
,,orks  out  of  the  most  dangerous  seismic  areas. 

2.  iiiarth  Dams  accurately  planned  and  well  constructed  are  structures  that 
were  proven  most  stable  and  worthy  of  confidence  by  the  earthquake  of 
April  18,  1906. 

3.  ''That  Concrete  kasonry  Dams  with  a  gravity  section  are  capable  of 

sustaining  the  most  dangerous  shocks  without  damage".  #1 

These  results  are  repeated  in  the  General  Report. 

un  account  of  its  importance  in  argument,  for  more  precise  information, 
and  for  the  purpose  of  instruction,  i  will  quote  at  the  end  of  this  section 
all  the  part  of  the  Special  deport  on  Water  <;orka  which  relate  to  the  S.  F. 
Earthquake  and  concerns  the  dams  of  Artificial  Lakes. 

This  document  is  already  decisive,  but  I  examined  attentively  also  the 
other  more  general  "Beport  of  the  State  Earthquake  Investigation  Commission" 
on  the  California  Earthquake  of  April  18,  1906  published  in  Washington  in 
1908.  It  is  a  monumental  official  publication  in  three  immense  volumes :- 
Volume  1  part  1A  and  2A,  and  Vol.  2  and  the  great  "Atlantic"  that  looks  at 
all  the  manifestations  of  the  earthquake  in  the  State  of  California  and  on* 
the  Nevada  Border. 

Index  23A  of  the  said  "Atlantic"  gives  a  resume*  of  the  intensity  of 
the  earthquakes  in  every  section  of  a  given  seismic  region.  It  shows  a 
large  area  of  Central  California  as  the  section  of  maximum  intensity. 

This  suddenly  reveals  that  what  has  been  said  has  no  sense  at  all  as 
far  as  basic  deductions  are  concerned,  for  all  through  Southern  California, 
where,  in  1906,  existed  only  rock  dams  so  much  praised,  -  the  Lower  Otay, 
Eacondido  etc.  the  seismic  phenomena  is  negligible,  (one  degree  of  the  Scale 
Hoasi-tforel)  as  it  is  in  northern  California,  while  in  the  Central  part  the 


32 

chart  showed  8°  to  10°  on  the  said  scale. 

Naturally  as  the  Rock  Darns  remained  indifferent  to  the  earthquake  - 
all  the  Earth  dams  tne  Gravity  Dams  of  Masonry  of  the  Arch  dams  most  daringly 
constructed  as  that  of  Bear  Valley  and  of  the  Upper  Otay  near  the  Hock  dams 
remained  absolutely  unaffected  by  the  iiarthquake  for  they  were  in  the  zone 
of  minimum  intensity. 

Abundant  signs  are  found  in  the  regions  greatly  affected.  But  even  here, 
I  repeat,  there  is  not  a  single  word  about  Rock  Dams  although  there  are 
extensive  descriptions  of  more  or  less  important  Sarth  Dams  and  of  Masonry 
Dams:  specially  that  of  Crystal  Springs  #1  which,  being  in  the  region  of  the 
heaviest  shock,  "was  uninjured  by  the  Earthquake,  a  careful  examination 
having  failed  to  reveal  a  ^2  crack  in  the  splendid  structure."  (Work 
cited  Vol.  1  part  la,  page  10E) 

It  is  of  special  importance  to  note  that  this  great  dam  is  of  reinforced 

• 

concrete  with  Monolithic  prisms,  20  ft.  by  12  by  12,  (6»00  by  3.60  by 
3,6  meters).  The  reservoir  has  a  capacity  of  24,  000,000,000  gallons 
{91  million  cubic  meters.) 

To  be  literally  scrupulous,  I  will  say  that  I  found  an  allusion  to  a 
partial  rock  composition,  but  not  a  word  on  Rock  Dams,  in  the  dam  dividing 
Crystal  Lake  in  two  parts,  a  dam  that  in  1906  was  simply  a  terrace  for 
walking,  -  the  water  being  of .  equal  height  in  the  two  parts  of  the  lake, 
(Vol.  1,  part  la,  page  102)  and  therefore  of  no  official  value  in 
retaining  the  water. 

Shis  dam  reportedm  in  the  publication,  as  made  of  an  agglomeration  of 
rocks  and  earth,  "was  displaced  but  not  badly  injured  by  the  earthquake". 
(loc.  cit.  page  93. ) 


After  the  authentication  of  the  real  facts  about  Rock  Dans  and  the 
S.  F.  earthquake  exactly  contrary  in  sense  to  the  assertions  made  in  the 
Propaganda,  this  last  statement  gives  me  a  chance  to  declare  that  the 


I 


33 


eventual  tentative  to  establish  an  analogy  between  earth  dams  and  rock 
dams  in  regard  to  the  way  they  withstand  earthquakes,  being  given  that 
both  serve  as  resorvoirs,  -  should  be  admitted. 

But  the  Rock  Dams  are  exactly  the  opposite  of  this,  especially  those 
with  a  vertex  on  the  high  line  of  development,-  a  thin  overlaying  of  wall 
a  few  decimeters  in  height  and  benind  it  amassed  some  large  rocks  as  the 
Scritti  L.L.  recommend  because  "the  body  of  the  dam  is  made  exclusively  of 
Rock".  (Scitti  N  (4)  page  20.  Mar.  1918,  page  67.—  Scritti  N  (6)  A.I.I, 
and  also  page  29  of  the  tistratto). 

This  Mural  keystone,  more  or  less  delicate  being  broken,  the  body  of 
the  dam  is  flooded  with  water  being  pushed  along  at  a  rate  of  from  20  to 
30  or  40  meters  per  second  by  the  velocity  of  the  wind.  Water  flowing  at 
such  a  rate  of  speed  will  quickly  disintegrate  the  most  resistant  mass  of 
rock  in  a  few  moments.  This  is  sufficient  evidence  without  addition  when 
one  considers  what  is  destroyed  by  a  jet  or  current  of  water  flowing  at  a 
rate  of  only  10  or  15  meters  a  second. 

While  on  the  other  hand  we  find  a  favorable  recommendation  for  well- 
constructed,  monolith  gravity  darns,  in  the  most  glorious  story  ever  written 
of  seismic  disturbances,-  that  of  the  3.  J?.  Earthquake,-  which  one  cannot 
even  imagine  without  the  aid  of  the  beautiful  photographs  collected  in  the 
two  reports  of  the  American  Engineers  and  of  the  State  Commission. 

Thera  is  no  such  recommendation  for  Rock  Dams.  In  fact  there  is  the 
assurance  of  their  certain  ruin  under  an  earthquake  shock  that  is  the  least 
bit  serious.   (He  is  wrong  here  Morena  Dam  takes  shocks  without  damage  — — 
O'Shaughnessy) • 

The  alluring  power  of  the  arguments  of  the  S.  tf.  Earthquake  have  been 
so  dangerous  and  attractive  that  the  same  Administrators  of  the  two  provinces 
who  are  opposed  in  tiiese  days  to  the  projected  High  Rock  Dams  are  .japposed  to 
this  type  because  even  if  they  were  justly  counseled  (or  recommended)  on 


, 


34 


account  of  their  adaptability  in  the  event  of  such  seismic  movement,  still 
they  have  not  been  tried  out  in  works  of  such  magnitude  etc»T-  Contradictions 
not  consistent  with  the  premise:  on  account  of  the  importance  of  the  size 
Of  the  work,  this  would  be  the  type  most  worthy  if  the  premise  were  exact. 

Another  point  is  the  effect  of  such  a  construction  on  public  safety. 

Therefore  it  is  noticed  that  in  the  part  of  California  seriously 
affected  by  the  earthquake,  rock  dams  did  not  exist  or  else  did  not  seem 
worthy  of  mention;  but  in  earth  and  gravity  dams  there  was  no  trace  of 
a  break. 

Appendix  of  the  Report  of  the  "Transaction"  of  December  1907  in  the 
"A.S.C.E."  Vol.  59  appendix  page  245. 


"Keport  of  the  Committee  on  the  Effects  of  the  Earthquake  of  April  18, 
1906,  on  the  Water  Works", - 

The  scope  of  the  investigation  used  as  the  basis  of  this  report,  is  to 
establish  the  different  values  of  the  divers  kinds  of  dams  used  in  water 
constructions,  as  regards  their  ability  to  withstand  earthquake  shocks  such 
as  those  that  shook  the  coast  of  central  California  on  the  morning  of  April  18 
1906.  Besides  this  we  must  draw  such  conclusions  as  will  help  to  ameliorate 
the  plans,  intensify  cautiousness,  or  give  more  faith  in  the  use  of  preceding 
plans  according  as  the  results  show  they  stood  the  shock. 

In  this  report  it  will  not  be  attempted  to  describe  in  detail  or  wven 
to  mention  the  different  structures  belonging  to  different  kinds  of  works  in 
use  for  utilizing  water  in  the  vast  area  so  violently  shaken.  The  first 
part  of  the  work  will  .best  be  fulfilled  by  the  description  of  various 
important  kinds  of  structures  from  which  the  Committee  has  reached 
conclusions  that  seem  most  logical* 

The  types  of  constructions  considered  are  Earth  Dams,  Elevated  I'owers, 
Masonry  Dams,  Distribution  Eeservoirs,  and  finally  Canalization. 

The  position  of  the  important  structures  mentione  from  now  on,  and 


their  position  as  regards  the  seismic  movement  are  indicated  in  the 
table  XL. 


JBarth  .Dams:-  Around  San  Francisco  there  Oxist  some  of  the  largest 
Earth  Dams  in  the  world.  In  the  peninsula  to  the  south  of  San  Francisco, 
and  between  San  Francisco  and  the  Pacific  Ocean  lying  along  the  line  of  the 
shock  and  adjacent  to  it,  are  three  Dams  belonging  to  the  Spring  Valley 
Water  Uo.  and  used  as  a  part  of  the  water  System  that  furnishes  water  to  the 

* 

city  of  San  Francisco,  'i'hese  are  the  Pilarcitos,  the  San  Andreas,  and  the 
Upper  Crystal  Springs  Dams. 

fj?he  displacement  having  been  along  a  permanent  longitudinal  seismic 
line  in  this  region,  6  or  7  ft.  in  width,  these  dams  must  have  been  terribly 
shaken,  especially  the  two  which  are  directly  in  the  seismic  line.  fi?he 
Pilarcitos  Dam  is  640  ft,  long  with  a  height  of  95  ft.  it  has  a  width  of 
24  ft.  at  the  top,  and  the  walls  are  at  an  angle  of  2  to  1.  It  has  an 
interior  clay  core  of  24  ft,  in  thickness  extending  40  ft.  under  the  bottom 
down  to  the  water-level.  It  was  constructed  in  1864-66.  It  is  from  1/3  to 
1  miles  west  of  the  line  of  fracture.  Shis  dam  was  not  damaged. 

The  San  Andreas  Dam  is  800  ft.  long,  93  ft.  high  and  of  the  same  type 
in  general  as  the  Pilarcitos.  It  was  built  between  1868-70.  ffhe  line  of 
fracture  passed  through  its  eastern  extremity  at  the  intersection  of  a 
natural  elevation  which  formed  a  part  of  the  Dam  at  this  point.  'Dhe 
convulsion  of  the  sufface  was  apparent  for  a  width  of  150  ft.  One  of  the 
breaks,  without  injuring  the  Dam,  went  through  a  conduit  made  of  reinforced 
concrete  with  iron  rails.  'JJhe  wood-covered  flumes  that  took  away  the  over- 
flow were  crossed  by  the  seismic  line,  fractured  and  dislodged  by  the 
general  movement.  rJ2he  body  of  the  Dam  shows  a  break  of  2  or  3  inches  in 
width  extending  longitudinally  along  the  central  line  of  the  whole  length 
of  the  Dam.  A  few  slight  breaks  occurred  in  the  opposite  direction.  As 
there  was  no  filtration  through  the  Dam,  the  entire  Dam  may  be  considered 


36 

as  good. 

The  Upper  Urystal  Dam  is  about  75  ft.  in  height,  about  600  or  700  ft. 
in  length  and  was  constructed  in  1878.  it  is  of  the  same  type  as  the  other 
two  already  described.  The  original  size  of  the  construction  is  now 
changed,  but  at  the  time  of  the  earthquake  the  water  was  the  same  height 
on  the  two  sides  so  that  the  Dam  was  not  subject  to  pressure  caused  by 
the  unbalanced  levels. 

Tnis  Dam  was  crossed  a  little  to  the  east  of  the  center  by  the  seismic 
line  and  the  two  parts  were  broken  leaving  a  space  of  6  to  7  ft.  The  top 
of  the  Dam  shows  many  longitudinal  and  transverse  breaks.  The  first  are 
not  continuous  and  appear  along  the  entire  length,  being  specially  noticeable 
on  the  sides.  Une  is  shown  in  fig.  1  of  table  41.  A  few  yeats  ago  this 
Dam  was  raised  several  ft.  so  as  to  improve  the  road  which  crosses  it.  It 
is  said  that  the  work  was  done  with  very  little  care,  and  that  it  would  not 
have  been  used  if  the  Dam  had  remained  as  it  was.  This  condition  and  the 
high  grade  of  saturation  resulting  from  having  submerged  between  the  two 
sides  are  considered  important  in  the  formation  of  the  longitudinal  break, 
the  walls. having  a  tendency  to  assume  a  more  horizontal  position  when 
subjected  to  a  strong  shock.  One  cannot  determine  by  these  circumstances 
what  resistance  the  Dam  would  have  had  against  water  pressure,  but  the 
nature  and  the  extent  of  its  visible  damage  are  not  so  grave  as  to  indicate 
that  if  the  Dam  had  really  been  working,  there  would  hafre  been  serious 
danger  of  a  break. 

In  addition  to  these  Dams  it  is  interesting  to  mention  two  little  Dams, 
each  one  closing  an  extemity  of  a  sandy  depress ion- farming  the  Saratoga 
Reservoir  of  the  San  Jose  Company,  placed  in  the  Santa  Gruz  Hills  between 
Saratoga  and  Los  Gates.  The  line  of  the  earthquake  crossed  this  reservoifr. 
and  cut  the  two  dams  at  right  angles.  At  the  eastern  extremity  of  the 
North  Dam  there  are  found  transverse  breaks  going  across  the  body  of  the 
Worth  Dam.  Figure  2,  table  41  shows  a  break  along  the  west  side  of  the 


• 


37 


North  Dam.     There  was  a  longitudinal  break:  through  the  Dam  and  quite  deep  on 
the  inside  of  the  wall.     The  transverse  break  is  shown  in  figure  1,   table  42. 
Although  the  Beservoir  was  full  at  the  time   ,   there  is  no  sign  that  the  water 
went  beyond  the  North  Dam.     At  the  southern  extremity  the  line  of  fracture 
passed  through  the  Dam.     A  pipe  of  cast-iron  of  10  inches  seems  to  have  been 
smashed.     A  joining  at  the  extreme  eastern  end  of  the  Dam  was  also  broken. 

These  breaks  of  conduits  resulted  from  the  reservoir  being  empty  and 
from  the  washing  away  of  a  considerable  part  of  the  material  of  the  South 
Dam  as  is  shown  in  figure  2,  table  42. 

On  the  east  coast  of  San  Francisco  Bay,   the  Gontra  Gosta  Water  Co., 
which  supplies  the  cities  of  Berkeley,  Oakland,  and  Alaraeda  with  water,  has 
two  Uarth  Dams,-  the  San  Leandro  or  Lake  Ohabot  Dam  and  the  Temescal  Dam. 
In  addition  to  these,  there  is  one    ,of  more  recent  date,-  the  Piedmont  Dam. 
The  first  of  these  was  constructed   in  1874-5  and   is  still  the  highest  Earth 
dam  in  the  world.     Its  summit  height  in  the  center  is  127  ft.  above  the 
ground  level.     On  April  18  the  lake  made  by  the  Dam  was  full  to  overflowing. 
The  shock  of  the  earthquake  raised  a  wave  of  3  1/2  ft.  high  which  broke 
over  the  Dam.     Neither  the  Dam  nor  any  of  its  accessories  were  hurt.     Ehere 
remained,  however,  evident  traces  of  the  earthquake. 

The  Temescal,  which  is  45  ft.  high,  was  constructed  in  1862.     This 
was  entirely  unharmed. 

3?he  Piedmont  Dam  is  of  recent  construction,   is  260  ft.   long  at  the 
crest,  45  ft.  high  on  the  interior  angle,  and  65  ft.  on  the  outer  angle, 
with  an  exterior  and  interior  incline  of  2  to  1.     The  interior  wall  was 
protected  with  6  inches  of  cement  having  a  finish  of  Concrete  instead  of  the 
usual  rip-rap.     The  Cement  was  in  squares  with  joinings  of  asphalt.     The 
Dam  had  been  completed  only  a  few  months,   and  had  been  filled  for  the   first 
time.     The  shock  that  it  received  caused  it  to  settle  about  6  inches  in  the 
center  and  produced  several  small  transverse  ard   longitudinal  breaks  naar 
one  end  of  jbhe  Dam.   There  was  no  break  in  the  Masonry  nor  in  the  material. 


38 

All  these  Dams  were  constructed  "by  the   staple  ;met hod  of  stretching 
them  in  thin  strata,  wetting  and  smoothing  the  layers  themselves  with  a 
roller.     Against  the  outer  walls  of  the  San  Leandro  and  Temescal  Dams  has 
teen  deposited  by  hydraulic  means  a  great  quantity  of  extra  material.   These 
two  Dams  have  an  interior  clay  core.     The  Piedmont  Dam  is  constructed  without 

any  core,   Taut  on  this  account   the  best  quality  of  material  is  used  in  the 
construction  of  the  upper  part  of  the  Dam. 

Masonry  Dams:     The  only  Masonry  Dams  that  were  shaken  seriously  in  the 
region  are  the  cement  dams  of  San  Mateo  or  Crystal  Springs  and  the  Bam  of 
Portola  or  Searsville   .     The  first  is  a  part  of  the  Water  System  that 
furnishes  water  to  San  i'rancisco,-  and  the  second  of  the  system  that  furnishes 
water  to  Stanford  University.     That  of  San  Mateo  is  one  of  the  highest  dams 
in  the  world,    its  height  being  planned  at  170  ft,  with  a  width  at  the   top 
of  25  ft.   and  at  the  base  of  176  feet.      Its  present  height   is  146  ft.;   its 
length  when  finished  will  be  680  feet. 

The  Portola  Dam  is  much  smaller,   its  height  being  50  ft.   although 
planned  higher.     Both  are  constructed  with  blocks  made  on  the  spot  and 
substantially  monolithic.     Each  one  of  these  is  situated  almost  paralell 
to  the  seismic  line  of  fracture  anl    at  a  few    hundred  feet  from  it.     Neither 
one  of  tit  se  Dams  gives  any  evidence  of  lesion     at  any  place.      It   is 
impossible  to  say  what  would  have  happened,   if  the  line  of  fracture  had 
crossed  it  transversely  at  right  angles  as  in  the  case  af  the  Earth  Dams 
already  described.     It  seems  reasonable  to  suppose  that  these  would  have  been 
hit  vertically  and  broiren  as  in  the  case  of  the  Earth  Dams,  nothing  worse 
than  a  gradual  loss  of  water  from  the  Beservoir  would  have  happened,   as 
the  two  structures  were  designed  with  abundant  gravity  sections. 

5.       Total  Denial  of  the  Assertions  made   in  the  Scritti  L.L.  concerning 
the  great  predominance  of  Rock  Dams  in  America. 


1.  Special  He  cent  American  i'exts. 

2.  The  Italian  Situation  as  regards  High  Dams. 

3.  Special  European  x'exts. 

4.  Biographical  References  of  the  Scritti  L«L. 

5.  Report  of  the  Proceedings  of  the  A.S.C.E. 

6.  Selections  from  the  last  year*s  "Eng.  News",  "Eng.  Records11  and 
"Eng.  News  Record". 

7.  Mention  is  lacking  of  the  Hock  JDams  of  Australia. 

In  this  section  I  justify  the  conclusions  c  and  d  placed  at  the  end  of 
paragraph  2  of  this  Report. 

My  conclusions  are  opposed  to  the  frequent  assertions  made  by  the 
Scritti  L.L.-  of  the  great  predominance  of  Rock  Dams  in  the  U.S.  and 
especially  in  California. 

The  Scritti  L.  L.  state  that  Rock  Dams  "so  common  in  the  U.S."  - 
"so  common  in  North  America"  (Scritti  N  (2  and  3) 

"Ehe  technical  periodicals  especially  the  "Eng.  ixecords"-  "The  Eng. 
News"-  the  classic  treatise  of  Wegmann  and  the  important  works  of  Schuyler 
and  Wilson,  but  above  all  the  "Documents  of  the  A.S.C.E.  of  New  York" 
offer  numerous  and  detailed  descriptions  of  these  Rock  Dams,  that  they  have 
come  into  current  use  and  have  the  absolute  faith  of  the  American  Engineers 
more  than  do  the  Earth  dams  or  those  of  Masonry."  (Scritto  N  (4)  page  6) 
and  then 

r10n  account  of  their  intrinsic  value  this  type  of  dam  is  rapidly 
spreading  and  taking  £h»  place  of  the  masonry  dams  used  in  the  past. 
(Soritto  N  (5)  page  81). 

The  principal  argument  used  to  prove  that  the  Engineers  have  unbounded 
faith  in  the  Rock  Dams  is  that,  already  cited,  of  the  &atun  Dam  which  is 
not  a  Hock  Dam* 

G-oing  further  into  the  "Scritti  L.L."  in  his  assertions  of  "frequent 
domination  of  Rock  Dams",  as  far  as  putting  them  to  use  is  concerned,-  a 
well  known  Projector  asserts  textually  with  didactic  boldness,  "that  if  one 
has  the  occasion  to  consult  the  technical  reviews  especially  those  aealing 
with  the  recession  of  barricades  (retaining  walls)  it  will  be  found, 


, 


40 


especially  as  far  as  what  is  done  in  America  is  concerned,  that  a  great 
number  of  Dry  Dams  are  constructed  instead  of  those  of  ordinary  masonry1*. 
There  is  no  hypothesis  about  which  are  circulated  such  assertions,  in  public 
discussions,-  and  also  there  is  an  excessive  confidence  placed  on  incorrect 
information,  diffused  ingnorantly  in  our  ov/n  country. 

It  is  true,  as  nas  already  been  said,  that  for  a  growing,  living 
subject  still  in  process  of  formation,  there  is  no  text  however  specific 
that  can  give  a  complete  idea  of  the  subject.  But  from  special  recent 
texts,  one  can  get  a  slight  knowledge  of  the  subject  sufficient  to  give  an 
idea,  near  the  truth,  of  the  predominance  of  one  type  or  other  of  Dams, 

Recent  Special  American  i'exts. Among  the  American  texts  that  I 

loaow  at  first  hand  at  this  time  I  will  mention: 

The  volume  of  Wegmann,  the  American  text  par  excellence  on  Dams 
brought  to  the  date  of  June  1911  (6th  Edition,  1911).  The  brief  chapter  on 
Rock  Dams  in  the  voluminous  work  begins :- 

"Within  recent  years  a  new  type  of  dam  has  come  into  use  in  the 
Western  States  of  the  Union". 

It  consists  of  14  pages  and  gives  an  idea  of  it  importance  in  the 
American  mind.  The  thin  catalogue  of  a  few  names  among  which  the  most  in 
evidence  are  the  Dams  of  Lower  Otay,  iiscondido,  korena:-  also  reports  a 
relatively  high  number  of  disasters,-  (about  which  the  reports  in  favor  of 
Rock  Dams  say  nothing) ,-  concerning  the  Walnut  Dam  whose  ruin  was  a  public 
disaster,  the  Ghatsworth  Dam  and  the-  Gastlewood  Dam,  to  which  can  be  added 
the  East  Canon  Greek  Dam,  ^destroyed,  reconstructed,  and  again  destroyed  a 
second  time.  (See  Sellew,  "Eng.  Mews  kar.  9,  1916  page  462).  To  this  list 
may  be  added  the  Strawberry  Dam  and  a  few  otners  like  tne  Relief  Dam  and  the 
Middle  Fork  Dam,  mentioned  in  the  .deport  of  1912  of  Engineer  J'Shaughnessy 
and  also  adding  the  destruction  of  the  Lower  Otay  while  mentioning  the 
miraculous  escape  of  the  korena  Dam  and  the-^scondido  Dam. 

vi/ith  only  Wegmann1  s  text  in  hand,  one  can  get  an  idea  of  the  real  and 


. 


; 


41 


very  insignificant  importance  of  the  itock  Dams  of  the  U.  S. 

Schuyler's  text  and  the  original  book  by  him  in  1896-97  confirm  the 
information  given  "by  Wegmann.  As  Schuyler's  work  refers  principally  to 
California,  there  is  proof  in  his  work  that  in  1896-97  in  California 
itself,  the  high  iiock  Dams  were  of  relatively  small  importance  as  compared 
to  the  Masonry  Dams. 

I  will  note  in  another  paragraph  a  judgment,  already  definite  in 
ochuyler  in  1897  f3  concerning  a  most  important  condition  necessary  for  the 
duration  of  fiock  Dams:-  a  splendid  condition,  but  so  difficult  to  apply 
that  it  was  neglected,  -  .i  will  not  say  in  the  destruction  of  the  Lower 
Otay  Dam  which  was  already  constructed  in  1897,  but  truly  in  the  Dam  of  the 
Morena,  finished  quite  a  bit  later  in  1912. 

In  two  splendid  recent  American  texts,  sta>-called  technical  editions  of 
recent  texts  on  the  hydroelectric  plants  for  reservoirs,  I  find  that  in  one, 
(Lof  and  ioishmore,  Hydroelectric  Stations  edited  by  Wiley,  Hew  York,  1917 J 
out  of  the  thirty  pages  dealing  with  American  Dams,  one-half  of  a  page 
deals  with  itock  Fill  Dams;  in  the  other  (Hydroelectric  Power,  by  Lyndon, 
edited  by  Me  (iraw-Hill,  Hew  York  1916  of  the  134  pages  of  notable  and 
original  character  in  Vol.  1  given  over  to  American  Dams,  almost  entirely 
gravity  dams,  or  concave  structure  with  spurs  etc.  the  earth  dsjns  and  those 
filled  in  with  hydraulic  fill  are  touched  upon,  but  there  is  not  even  one 
line  about  Rock  Pill  Dams. 

With  a  direct  knowledge  of  American  texts  up  to  date,  on  the  problem 
Of  dams  in  North  America,  even  the  beginner  must  have  already  made  up  his 
mind  as  to  the  influence  of  the  propaganda  of  the  "Scritti  L.L."  among  us. 

"The  Italian  Situation  on  the  Subject  .of  High  Dams. H 

Even  the  European  special  texts  are  not  so  backward  and  badly  informed 
as  to  give  a  false  opinion  about  the  actual  American  technique  on  High  Dams. 
In  the  past  there  were  but  two  works  on  Dams,  one  of  Crugnola  1883  and  one 


42 

and  one  of  Torricellit  1885,  which,  were  opposed  to  each  other  in  many  ways,  fl 

The  Author  hopesthat  in  the  future  Italians  will  publish  only  works  of 
the  utmost  accuracy  and  that  they  will  get  all  their  information  at  first  hand. 
Having  a  knowledge  of  the  tongues  foreign  works  are  written  in,  becomes  an 
absolute  necessity.  They  must  disseminate  their  knowledge  through  public 
libraries  and  conferences. 

The  future  Italian  work  must  be  rendered  with  integrity  and  technical 
capacity,  with  elaboration  first  hand  and  with  a  direct  knowledge  of  the 
situation  of  the  many  questions  connected  with  the  dams.  It  shall  be  a  very 
hard  enterprise  of  great  persistancy  worthy  of  the  efforts  and  of  the  spirit 
of  young  men  who  will  study  and  manage  the  art  with  courageous  and  clear 
understanding  and  will  know  how  to  join  or  to  match  the  genius  of  the  method 
and  have  the  patience  for  the  analysis. 

First  of  all,  they  should  make  themselves  masters  of  hardship,  according 
to  the  expression  of  the  renowned  teacher  Carduci.  We  are  sure  that  the  coming 
future  will  give  to  us,  and  for  us  modern  and  organic  treatise  upon  these 
great  dams.  In  the  meantime,  we  should  be  satisfied  with  the  partial  knowledge 
upon  questions  more  effective.  Briefly,  while  it  would  be  very  useful  to  have 
some  technician  who  have  familiar  contact  with  the  language  make  careful 
translations  and  clear  resume1  of  the  argument,  we  should  with  the  experience 
thus  in  our  hands  not  lament  over  the  repeated  propaganda.  With  the  sketches 
of  the  designs  which  the  one  concerned  should  procure  by  all  means  in  the 
foreign  text  that  oan  be  procured,  these  last  designs  should  be  displayed  in 
the  libraries  of  the  schools  and  the  colleges  of  the  engineers  in  the 
Electric,  Technical  and  among  the  Constructing  Societies.  At  least,  until 
we  shall  have  an  Italian  text  worthy  of  the  subject.  Such  methods  of 
diffusion  (false  scientific]  can  certainly  strike  the  public  not  familiar  with 
the  facts  to  which  I  allude.  But,  such  public  do  not  peason,-  what  is  verse, 
know  nothing  of  the  subject.  As  would  happen  to  me  by  misfortune  an  examina- 
tion would  be  brought  to  me  and -I  would  fail. 


: 

.       - 


43 


One  speaks  of  a  subject  in  a  careless  way  because  lacking  the  data 
which  technical  and  scientifical  collaboration  would  provide  from  those 
who  have  overtaken  or  grasped  the  technical  or  scientifical  point  of  view; 
the  altenative  is  a  useless  variety  and  sometimes  harmful  to  the  country 
when  one  is  informed  in  incorrect  methods, 

"Special  European  Texts". 

Turning  from  this  reflection  on  the  Italian  situation  in  regard  to 
Dams,  let  us  turn  to  European  texts  that  treat  of  American  technique  and 
we  will  find: 

That  the  text  of  Bellet  (1907),  a  little  backward,  but  which  considers 
the  new  American  Dams,  gives  only  a  few  lines  (on  page  28)  to  the  fioclc 
Fill  Dams: 

That  the  ample  text  of  Zeigler  (Talsperrenbau  1911)  gives  to  the 
same  subject  only  a  few  lines  found  on  page  121; 

So  also  the  Mattern — Rohbock  (Talsperrenbau  1912). 

The  large,  splendid  work  of  Ludln  (Wasser  Krafter,  1913)  work 
produced  from  great  collaboration  which  devotes  page  after  page  to  a  few 
thousand  references  to  American  literature  on  Dams,  makes  an  allusion  to 
Rock  Fill  Dams  (pages  1033  and  1037)  with  the  three  or  four  usual  names, 
Escondido,  -^ower  Otay,  East  Canon  and  Pecos. 

A  workof  great  size,  Engel's  Handbuch  des  Wasserbaues,  (1914)  names 
only  the  Lower  Otay  (page  621). 

All  these  special  European  and  North  American  texts  must  be  in  accord 
to  distort  the  truth  when  they  show  how  relatively  unimportant  the  Hook 
Fill  Dams  are,  compared  to  all  the  others,  if  the  opposite  is  true  that  is 
found  in  the  "Scritti  L»L.ft  and  in  those  that  use  the  latter  as  guides. 

The  Biographical  References  of  the  Scritti  Luiggi. 

But  of  placed  in  supposition  such  collective  agreement  for  a  complete 
alteration  of  the  truth  in  the  -special  American  texts,  or  if  we  examine 


44 


tiie  collection  of  newspapers  Eng.  News,  Eng.  Record,  Eng.  News  Record  that 
there  was  in  Oct.  1917  and  above  all  the  Atti  (contract)  of  the  A.S.C.E. 
according  to  the  recommended  determinations  of  the  Scritti  L.L. 

One  should  notice  in  the  first  place  the  fact  that  this  perseverance 
but  common  recommendation  searches  the  already  mentioned  collection  of 
periodicals,  that  is,  newspapers  which  do  not  come  out  concerning  the 
fundamental  and  general  treatise  which  are  one  continued  repetition  quoting, 
also  many  times  in  the  same  scritto. 

"See  Itti  A.S.C.E.  1912".  It  is  said  already  the  Scritto  N  3  page  10 
of  the  Estratto. 

"See  Atti  A«S.C.E.  1912".  It  says  the  Scritto  L.L.N.  4  which  is 
founded  on  page  7. 

"See  the  Atti  A.S.C.E.  1912.  It  says  the  same  Scritto  N.  4  page  11. 

He  who  has  eagerness  or  aims  to  study  retrospective  to  have  more 
information  on  this  question  can  consult  the  article  of  the  A.S.C.E*  1912 
which  is  the  same  as  Scritto  N  4  page  21. 

"See  the  Scritto  N  5  page  82  for  the  writing  from  A.I.I.  Mar.  16,  1917 

Also  in  the  last  No.  6,  always  referring  to  Rock  Pill  Dams,  "the  most 
economical  and  the  most  secure  against  all  eventualities  of  seismic  shocks" 
he  refers  again,  as  he  always  does,  to  "Documents  of  A.S.C.E.  number  of 
March  1,  1918.  A.I.I. 

In  all  the  other  Scritti  there  is  one  other  special  reference  (Scritto 
N  (4)  page  9)  to  the  "Eng.  News"  Oct.  15,  1916,  about  the  Otay  Dam,  a  refer- 
ence non-existing  as  has  already  been  shown;  and  there  is  another  to  the 
"Eng.  Record"  of  Sept.  9,  1912  for  a  Dam  of  Clay  and  Rock. 

Enough  said: 
Report  of  the  Proceedings  of  the  A.S.O.E 

Therefore  if  one  wants  to  get  a  complete  and  direct  knowledge  of  the 
whole  argument  he  will  be  led  from  the  Scritti  L.L.  to  the  Transaction  or 
Proceedings  of  A^S.C.E.  1912,  where  he  will  find  only  the  Report  of 


: 


' 


41 

Engineer  O'Shaughnessy  on  the  Rock  Fill  Dam  of  Morena,  a  report  with  which 
the  Soritti  is  not  familiar  as  is  shown  clearly  by  their  report  on  the 
Lower  Otay  and  on  the  same  Morena  Jam  in  regard  to  earthquakes  etc.  Now 
this  report  of  O'Shaughnessy  and  Correspondence  relating  to  it,  making  up 
a  synthesis  of  all  the  modern  doctrine  on  Hock  Fill  Dams,  is  an  excellent 
special  monograph  on  the  Morena  Dam,  nowever  slightlykt  jjs_  glanced  at.  from 
the  general  point  of  view. 

There  are,  besides  the  above,  three  most  important  reports  on  Masonry 
Dams  in  the  "Transactions"  of  1913:- 

The  first  on  the  treatment  of  the  under  support  of  masonry  Dams 
promoted  by  Harrison  and  on  the  pressure  of  ice  against  the  reservoir  dams:- 

The  second:  The  important  report  of  Houston  and  the  discussion  relating 
to  the  Halligan  Reinforced  Concrete  Dam: 

The  last,  an  important  Report  by  Parsons  on  the  calculation  of  the 
strength  in  reinforced  concrete  dams* 

Anyone  who  looks  through  the  Proceedings  or  Transactions  for  the  last 
twenty  years,  and  in  the  "Annales  des  fonts  et  Chaussees'1  which  every 
Engineer  should  regard  as  a  masterpiece  of  his  art,  will  find  only  the  modest 
little  writing  of  1912  which  refers  to  Rock  jj'ill  Dams,  while  he  will  find 
many  important  studies  on  Masonry  Dams.  After  1912,  there  is  a  profound 
silence  on  Rock  Fill  Dams  while  there  are  added  works  on  Gravity  Dams,  on 
Reinforced  Concrete,  or  Arch  Dams  on  Multiple  Arches,  and  most  notably  in 
the  most  recent  number  of  May  1918,  the  works  of  Jorgensen  on  a  Dam  with  a 
constant  angle  arch.  I  gave  the  date  1910,  because  I  consider  a  space  of 
ten  years  as  long  enough  to  fix  approximately  the  technical  situation  of  a 
given  argument. 

Finally  the  conclusion  is  convincing  as  to  the  poor  amount  of  data  on 
Rock  Fill  Dams  disclosed  by  an  examination  of  the  index  to  the  Tranasctions 
of  the  A.S.^.E.  for  the  two  periods  1901-1LJ07,   1867-1901 

Grleamings  from  the  "Eng.  Hews",  the"Bng.  •£iecord"  and  the  "Eng.  Kews 
Record"  of  the  last  year. 


. 


46 


Ihe  Reports  of  the  rroceedings  of  A.S.C.E.  give  a  "broad  insight 
into  the  application  of  the  given  principles:  to  dam  construction:  i.e. 
Take  the  Arch  Dams  in  one  report  of  1914  on  the  Arch  Dams  of  Huacal;  we 
find  in  the  text  discussion  and  valuable  statistics  which  bring  out  the 
peculiar  application  of  tnis  type  of  Dam  to  North  America. 

Besides  this  we  have  the  weekly  numbers  of  the  "Eng.  News",  the  "Eng. 
Record",  and  the  "Eng.  News  Record",  which  by  their  articles  and  their 
technical  data,  and  by  signaling  any  new  fact  or  notable  construction,  gives 
us  as  war  glance  through  the  reports  of  a  few  years,  the  exact  number  and  the 
different  kinds  of  High  Dams  used  in  America. 

In  looking  through  the  numbers  for  the  last  five  months,  I  did  not 
succeed  in  finding  anything  about  notable  new  constructions  except  the 
sing3e  one  of  Strawberry  Rock  Dam  which  in  1916  was  not  advanced  in 
construction,  and  of  which  there  is  nothing  more  in  the  periodicals,  but 
of  which  I  have  learned  through  private  research,  I  will  add  the  following: 

A  small  dam  of  rock  fill,  lo  meters  high  (43  ft.)  with  a  nucleus  of 
masonry  and  earth  (Eng.  Record,  Dec.  25,  1915).  A  modest  dam  of  65  ft. 
(about  20  meters)  in  Goose  Lake  Valley,  Oregon,  that  is  not  properly 
speaking  a  rock  dam,  but  a  Dry  Rubble  Wall  on  a  solid  rock  foundation,  as 
are  all  American  Dams.   (Eng.  News,  Jan.18,  1917-r  A  modest  temporary  beam 
(not  dam  such  as  we  are  here  considering)  over  the  Colorado  River.  The 
Government  of  the  interested  States  refused  for  five  years  to  grant 
permission  to  construct  the  crossbeam  of  rock,  only  the  temporary  permission 
for  which  was  given  on  account  of  the  difficulty  of  constructing  because 
of  the  existing  water  conditions  of  trie  River.  (Eng.  News  Sept.  28,  1916, 
page  622. ) 

I  have  looked,  as  I  say,  with  utmost  care  from  June  1913  in  the  "Eng. 
News",  "Eng.  Record"  and  the  "Eng.  News  Record"  because  the  construction  of 
new  Rock  Dams  interested  me  on  account  of  the  difficulty  of  getting 
information  concerning  them,  and  1  should  be  very  happy  if  some  one  could 


. 

•    • 


' 


47 

enrich  the  ..eager  data  of  them  with  significant  additions;  wiiich  data  is 
becoming  loss  and  less  in  regard  to  the  entire  construct!  on  of  High  Dams 
specially  masonry  darns. 

As  a  conclusion,  I  will  say  that  it  seems  to  me  to  be  a  great  exaggera- 
tion in  favor  of  Rock  Dams  to  say  that  1  out  of  100  is  their  proportion. 

I  will  cite  other  notable  cases  that  will  serve  to  judge  other  unfound- 
ed assertions,  like  the  preceding,  in  the  propaganda  of  the  Scritti  L.L.;  - 
about  the  placing  of  gravity  dams  among  the  dead  timbers,  about  the  use  of 
great  altitudes  etc.  I  will  be  more  specific  about  the  references  for  the 
last  years,  for  which  I  can  get  exact  information  from  the  chronicles. 

The  immense  Arrow  Hook  Dam  of  Oct.  17,  1915,  and  which  cost  almost  five 
million  dollars,  is  a  gravity  darn  with  an  arched  plane  made  of  Cyclopean 
cement.  It  is  348.5  ft.  (106.39  meters)  high,  on  a  rock  foundation  of  250  ft. 
(76.25  meters)  along  the  course  of  the  dam.  It  is  in  Idaho,  a  Western  State, 
at  an  elevation  of  3200  ft.  i almost  1000  meters).  (See  Eng.  News  Record 
Sept.  20,  1917.  Eng.  ftews  Oct.  7,  1915,  and  Eng.  News  Jan.  16,  1913). 

The  large  Elephant  tfutte  .uam  finished  May  13,  1916  is  304  1/2  ft.  high 
(92.87  meters)  on  it  foundation  and  203  1/2  ft.  (62.08)  M.  on  the  bed  of 
the  river.  It  is  a  Gravity  Dam.-  It  is  at  an  altitude  of  4,  141  or  1350  m. 
(Eng.  News  May  18,  1916)  June  19,  1903,  Jan.  16,  1913.  It  is  situated 
in  the  western  state  of  New  Mexico. 

The  large  King's  River  Dam,  located  in  the  San  Joaquin  Valley,  Calif., 
according  to  the  project  of  the  U.-S.  Reclamation  Service  will  be  305  ft. 
high  (93  m)  is  a  Gravity  Dam  with  an  arched  base  situated  in  the  highest 
region  of  the  Sierra  Nevadas  between  5000  and  14,000  ft.  in  elevation.  At 
the  present  moment  I  have  not  the  precise  height  and  cannot  find  it  in  the 
"Eng.  News"  of  Jan.  18,  1917,  pages  1.2.3)  and  in  the  Reports  of  the  U.S. 
Reclamation  Service. 

The  "Three  Miles  Falls"  is  an  immense  Dam  of  multiple  arches  in  the 
mountains  of  Oregon  in  the  j?ar  West  (Eng.  News  May  27,  1915). 


The  Dams  of  Gem  Lake  and  Agnew  Lake  of  the  same  type  at  an  altitude 
of  9,050  ft.  (about  3000  meters)  are  also  in  Calif.  They  are  constructed  of 
reinforced  concrete,  finished  in  i*ov.  1916.  (Eng.i\lews,  Dec.  21,  1916). 

The  new  dam  in  Bear  Valley  of  multiple  Masonry  arches  is  at  an  altitude 
of  6743  ft.  i2044  m)  is  also  in  Calif.  iEng.  i<iews  May  18,  1916) 

Of  this  same  type  in  California,  and  of  great  height,  is  the  Tule  Lake 
Dam,  (Bng.  News,  April  30,  1914). 

The  article  by  Eng.  Bowen,  most  important  for  the  discussion  of  sedimen- 
tary deposits  in  reservoirs,  in  the  Eng.  Becord  of  July  26,  1917,  gives 
incidentally,  information  ahout  a  recent  Gravity  Dam  (120  ft)  with  an  over- 
flow ad.  lib.  {Overflow  type  —  a  type  which  is  spreading  in  North  America), 
in  the  inolumne  Mver  section  in  the  Sierra  itevadas,  California,  at  the 
extraordinary  altitude  of  $ore  than  9000  ft. 

The  large  Spaulding  Dam  is  a  most  recent  Gravity  Dam  of  concrete  in 
the  Sierra  ^evadas,  Calif,  at  an  altitude  of  4680  ft.  (about  1500  meters) 
with  about  a  height  of  from  225  ft. to  260  ft.  (7930  m. )  (Eng.  News  Kecord, 
Aug.  9,  1917.  It  will  reach  an  altitude  of  325  ft.  according  to  the  planw. 
Eng.  Hecord  Aug.  9,  1913). 

Other  important  Gravity  Dams  with  arched  bases  are  also  in  California. 
The  Big  Creek  Dam  in  the  Sierras  at  an  elevation  of  6,910  ft.  (about  2100  m. ) 
will  reach  a  height  of  115  ft.  from  the  river  bed,-  constructed  in  Uyclopean 
cement.   (Eng.  Itecord,  Jan.  10,  1914). 

She  Klamath  Kiver  Gravity  Dam,  arched  base,  rising  130  ft.  in  a  most 
elevated  region  of  northern  California.  (See  Eng.  Hecord  June  7,  1913). 

The  White  Salmon  River  Dam,  125  ft.  high,  a  Gravity,  arched  base  Dam 
in  the  highesfr  region  of  the  Far  West  (Wash. ) (See  Eng.  Record  act. 11,  1913.) 

The  Eng.  i\lews  Hecord  of  Aug.  9.  ,  1917  gives  notice  of  another  dam  of 
multiple  arches,  in  reinforced  concrete  of  Rock  Creek,  Northern  California, 
at  an  elevated  altitude. 

The  Eng.  News  of  Aug.  17,  1916  gives  notice  of  the  immediate  construe- 


49 


tion  of  a  big  dam  about  250  ft.  (75  meters]  in  the  errand  Canon,  Colorado 

with  the  information  that  it  will  be  either  of  cement  or  masonry*  So  also 

the  Eng.  i^ews  of  July  30,  1916  speaks  of  the  Ketch  Hetchy  Dam,  300  ft. 

high  (91.5  meters)  in  the  high  mountains  for  a  new  reservoir  which  will 

furnish  water  to  San  Francisco,  California. 

She  Jadkin  River  Ham  of  Carolina  is  a  Gravity  Dam  with  an  over- fall  of 

169  ft.  (Eng.  Hews  of  i><ov.  16,  1916.) 

Eagle's  Nest  Dam  in  the  cimarron  Valley  -( New  Mexico)  is  an  arched 
Cyclopean  concrete  construction.  Its  height  is  140  ft.  It  is  afe  an 
elevation  of  more  than  6000  ft,  (Eng,  .uews,  Jan.  11,  1917  and  Eng.  News 
Becord,  x>ec.  6f  1917). 

Salmon  Creek  Dam  (California)  is  an  Arch  Dam  with  a  constant  angle 

(Eng.  news,  kar.  11,  1915).  See  the  Heports  already  mentioned  of 
Jorgensen  in  the  P.  C.  E.  of  1915  in  which  many  other  dams  of  new  arch 
type  are  mentioned. 

The  State  Projects  for  the  Heservoirs  of  West  Work  in  San  Bernardino 
County,  California  (Report  of  the  Board  of  Supervisors  of  San  Bernardino 
Co.)  contemplate  the  erection  of  a  large  Gravity  Dam  in  one  of  the  highest 
regions.  (Engo  tiews  iiecord  June  24,  1918). 

Another  Arched-Grauity  type  is  that  of  Union  uap  near  North  Yakima, 
(Wash,  j?ar  West)  a  section  of  great  height  where  they  show  that  it  will 
take  7,271  cubic  yards  of  cement.   (Eng.  news  record,  Aug.  16,  1917).  A 
new  dam  of  multiple  arch  type  serves  the  Salt  Lake  Aqueduct.   (Utah,  Far 
West].  It  is  145  ft.  high  (Eng.  News  record  Mar.  7,  1918)  and  at  a  great 
elevation.  Another  new  dam  of  arched  masonry  type  for  the  aqueduct  itself 
is  that  of  Big  Cottonwood  Canon  at  an  elevation  of  9,4b6  ft.  (2,850  m. ) 
(Eng.  iiecord  Sept.  9,  1916 j. 

The  Eng.  .wews  Aiecord  recently  points  out  that  the  multiple  Arched 
Eeinforced  concrete  type  of  dam  is  growing  in  the  west. (Eng.  ^ews  iiecord 
March  7,  1918). 


50 


construction  of  concrete  dams  must  be  very  great  because  the 
Amours  on  uo.  snows  that  it  alone  nas  constructed  100  concrete  darns,  ilng. 
Hews  record,  $une  13,  1918,  page  105  of  tiie  advertisements. 

ihe  same  number  of  &.  ni.  x..  June  13,"  1918  advertise  a  house  that 
handles  auto-cars  for  construction  purposes,  speaks  of  the  construction,  on 
the  Pitt  iiiver  near  the  Dig  tfend  in  the  mountains  of  northern  California, 
of  a  giant  concrete  dam  costing  ^17,000,000  by  the  Pacific  (ias  6c  Electric 
Co.,  showing  in  the  annexed  photograph  30  auto-cars  transporting  material 
up  the  difficult  steep  incline  of  the  Pitt  iiiver  mountains. 

I  have  maintained  this  long  quotation  particularly  of  cases  in  the 
"estern  Litates,  and  more  particularly  in  California  which  is  but  a  small 
fraction  of  the  same,  for  the  evident  purpose  of  comparing  them  with  the 
Scritti  L.L.  well  put  together  in  Section  U  (4). 

The  passage  quoted  from  Wegmann  says  that  the  Hock  Pill  Dam  type  is 
the  type  born  in  the  Far  West:  in  f.r.ct  no  example  can  be  found  of  its 
application  to  recent  constructions  outside  of  the  Bar  West. 

Information  is  lacking  on  the  lack  Fill  Dams  of  Australia. 

She  American  'fechnical  Papers  that  give  ample  notice  of  any  notable 
constructions  in  other  sections  where  the  English  language  is  Used,  speak 
often  of  Australia:  but  I  have  found  no  mention  of  &Qok  Fill  Dams  in 
Australia, 

In  the  Scritti  Luiggi  (N  (4)  page  16  arid  in  the  notes)  the  subject 
of  the  projected  construction  of  the  California  Sugar  Loaf  Sock  Fill  Dam  is 
often  mentioned.  Begun  in  1914,  and  stopped  on  account  of  the  great  suspense 
caused  by  the  War,  shows  how  this  type  of  construction  is  spreading. 

This  project  of  the  Sugar  Loaf  Jam,  according  to  direct  reports  was 
burr led  as  soon  as  started.  It  is  notable  that  the  Dam  itself  and  the 
diffusion  of  the  Rock  OJype  Dam  have  left  no  trace,  even  in  the  American 
Papers  which  would  gladly  have  mentione  the  exploitation  of  a  California 
type  of  construction. 


51 


I  find  instead  for  Australia:  - 

(Chore  is  a  great  State  Project  (by  the  Conservation  and  Irrigation 
Commission)  for  New  South  Wales  of  a  Cement  Reservoir  Dam  in  the  Upper 
Murray  Section  (Eng.  News  Record,  Alay  31,  1917,  page  437). 

The  magnificent  Brisbane  Dam  in  Australia  begun  Dec.  1916,  is  125  ft. 
high  is  a  Gravity  Dam.  of  Cyclopean  Concrete.  It  is  in  the  mountainous 
region  of  Cabbage  Tree  Creek  and  with  the  accessories  costs  838,000.  It 
is  fully  described  in  the  Bng.  News  Record  of  Aug.  9,  1917  page  248. 

This  paragraph  of  direct  quantitative  evaluation  does  not  pfcetend  to 
be  statistically  perfect:  such  perfection  does  not  exist  as  he  w&ll  Imows 
who  undertakes  such  research.  But  kept  within  the  most  accurate  bounds 
possible,  this  paragraph  is  a  severe  criticism  of  affirmations  in  the 
Scritti  L.L.-  and  in  v/orks  derived  from  them,  that  the  Rock  Dams  predominate 
in  America  and  that  Gravity  Dams  and  others  are  a  dying  type  etc»  One  can 
not  be  indulgent  in  words  that  deal  with  this  matter,  but  there  is  no  wrong 
intended.  Instead  v/e  have  profound  sorrow  when  we  think  of  the  method  that 
was  employed  and  of  the  weight  it  carried  in  the  construction  of  Dams. 

In  fact  such  deviation  from  the  truth,  -  more  fantastical  than  the 
California  stories  of  Bret  Harte  have  become  among  us  (the  Italians)  of  real 
technical  value,  as  shown  in  the  daring  of  q^tifce  a  numfrer  of  projects  that 
have  reached  this  office. 

6.   The  Construction  of  High  Dams  in  the  Work  fcf  the 
U.S.  Reclamation  Service. 

The  Orohydrograpnic  and  Demographic  character  of  the  Far  West 
and  the  insignificant  use  of  Rock  Dams  for  Reservoirs. 

Legislation  in  the  Ui  S.  that  affects  Dams. 

Recent  Consequences. 

There  is  in  the  u.  3.  a  recent  governing  institution,  the  U.  S. 
Reclamation  Service  that  took  the  initiative  in  the  Reclamation  Act  of 
1902,  which  proposed,  in  the  interest  of  the  Public,  to  construct  large 


52 


the  motive  force  used  etc. 

In  a  few  years  up  to  June  30,  1917,  the  cost  of  construction  amounted 
to  123  millions  of  dollars  spent  intelligently  to  irrigate  an  area  of  neatly 
1,  800,  000  acres  (page  45). (An  acre  equals  0.405  hectares)  with  an  imposing 
hydraulic  power. 

The  Reclamation  Service  took  for  its  exclusive  field  of  operation  the 
western  states  of  Oregon,  California,  Nevada,  Utah,  Colorado,  Wyoming, 
Arizona  and  Montana. 

In  1900,  these  States  had  a  total  population  of  4,  091,  000  #2  (2p  45) 
for  an  area  of  3,  076,  000  square  kilometers,  -  eleven  times  the  area  of 
Italy,  -  with  an  average  of  1.3  inhabitants  per  kilometer,  which  is  the 
hundredth  part  of  ours.  But  this  number  is  still  far  from  giving  a  real 
idea  of  these  ffalleys  for  the  reservoirs  were  placed  even  in  the  deserted  or 
thinly  populated  Galleys  that  had  a  great  oronydrographic  value.  The 
altitude  of  most  of  these  places  was  great,  being  estimated  at  more  than 
1500  meters.  It  was  like  an  immense,  high  island  that  had  in  itself  anil 
area  about  1500  meters  about  1/2  of  the  entire  area  previously  mentioned, 
and  about  5  times  the  area  of  our  country. 

The  real  idea  of  this  Country  is  found  in  the  Annual  Reports  of  the 
same  Reclamation  Service  and  in  the  publications  of  the  U.  S.  Geological 
Survey  that  illustrate  the  Greo-hydrographics  of  any  part  of  the  American 
Country.  These  reports  show  the  said  fields  of  work  and  those  where  our 
oronydrographic  works  are  placed,  --also  the  slight  little  secondary  or 
tertiary  valleys  that  need  our  reservoirs  where  at  distances  relatively 
ahort,  are  found  little  .villages  more  or  less  thickly  populated. 

Hiere  I  will  limit  myself  to  Storage  i)ams  for  artifical  reservoirs 
as  distinguisned  from  the  Diversion  Dams  such  as  the  U.  S.  Rec.  Service 
constructs  in  immense,  almost  deserted  regions.  The  extraordinary  elevation 
at  which  the  most  remarkable  arched  masonty  dam  in  the  world,  the  Roosevelt 
East  Park,  Arrowrock,  Sun  River,  Pathfinder,  Elephant  Butte,  Shosnone, 


Kingfs  Eiver,  etc.  are  placed,  is  marvelous.  For  Storage  Dams  of  less  promi- 
nent size,  many  earth  dams  are  used,  but  planned  with  great  s^ill,  with 
stately  dimensions,  and  carried  out  with  great  care.  Those  of  Rtock  which 
already  existed  and  wnich  came  v/ithin  the  irrigating  system  of  the  U.  3* 
Hec.  Service  are  relatively  insignificant,-  'i'he  Minidoke  Dam  25.8  meters, - 
the  Clear  Lake  Dam  10»00  meters,-  others  of  mixed  earth  and  rock,  not  to  be 
confounded  with  the  pure  rock  type,  which  is  analyzed  here  auch  as  the 
IJieton  Dam  so  important  in  construction, 

I  rely  entirely  upon  the  index  of  the  Storage  Darns  page  453-454  in  the 
last  Report  of  1916-J.917,  ana  on  the  Heport  gotten  from  the  Reports  themselves 
But  the  most  daring  construction,  as  regards  height  of  the  Retaining  or 
Storage  Dams  is  usually  of  some  masonry  construction  generally  of  the 
Gravity  type  with  an  arched  base. 

I  must  be  satisfied  with  this  rapid  glance  at  tne  U.  3.  Reclamation 
Service  Article  which  really  merits  a  good  deal  of  consideration.  It  seems 
to  me  that  the  work  of  the  U.  53.  Reclamation  Service  is  an  indication  of 
the  calm  reflection  of  ajvery  erudite  people. 

There  where  the  canon  areas  end  and  where  the  highlands  are  practically 
deserted,  as  compared  to  the  little  table-lands  of  our  country  which  are  so 
full  of  life  at  every  turn,  the  important  dams  are  of  masonry  having  an  air 
of  security  and  permanence.  It  is  probably  because  they  expect,  as  Carnegie 
predicts,  that  in  a  short  time  there  will  be  a  billion  inhabitants  in  the 
United  States* 

As  far  as  the  construction  of  dams  is  related  to  public  safety,-  the 
postulate  conceives  only  structures  of  an  absolutely  permanent  nature  and 
has  no  use  for  structures  that  will  last  only  a  relatively  long  time. 

Certainly,  as  I  have  already  said,  just  the  simple  knowledge  of 
geographic  and  demographic  factors  made  it  possible  in  the  past  and  explain- 
able up  to  a  certain  point,  that  certain  public  enterprise»s  and  some 
private  citizens,  stimulated  to  boldness  by  lack  of  conscience  and  by  the 


mania  for  money,  (which  is  unscrupulous  in  all  countries)  snould  have  made 
faulty  dams  and  constructions.  x'hen,  indeed,  the  type  of  dam  constructed 
does  not  matter,  for  the  urravity  Dam,  the  Arch  Dam,  the  iteinforced  etc., 
all  become  destroyed,  if  they  are  constructed  on  faulty  plans,-  or  are 
constructed  fraudulently  or  carelessly  on  good  plans. 

in  the  1).  o.  almost  immediately  and  still  today,  is  felt  the  effect  of 
that  period  of  absolute  license  wnen  Construction  societies  and  Individuals 
could  construct  Dams  without  any  legal  restraint. 

I  omit  here  all  quantitative  analysis  of  the  destruction  of  dams  which, 
would  require  more  space  than  this  Report  fills,  "but  I  will  note  that  in 
one  rainy  season  in  the  Spring  of  1912,  eighteen  dams  collapsed  in  the 
Eastern  States,  besides  a  few  in  the  Autumnal  rains. 

The  Bug.  Hews  of  Nov.  21,  1912,  states,  "These  are  exceptional  cases, 
but  hardly  a  day  passes  when  some  article  concerning  the  destruction  of  a 
Dam  is  not  sent  to  this  office.  We  are  convinced  that  taking  it  all  in  all, 
there  is  more  Carelessness  of  engineering  in  the  drawings  and  construction 
of  dams  than  in  any  other  construction.  1'here  results  &  greater  damage  to 
property  and  greater  loss  of  life  from  such  carelessness  than  results  from 
all  the  carelessness  found  in  all  other  kinds  of  construction  taken  together. 

Hardly  had  these  facts  been  brought  to  the  notice  of  the  U.  3.  Government 
when  the  latter  passed  a  legislative  measure  governing  the  construction  of 
future  dams  and  ordering  special  vigilance  measures  for  the  dams  already 
constructed.  Such  laws  have  often  teen  added  to  by  the  State  Departments  of 
Engineering,  as,  for  example,  may  be  seen  in  the  Report  of  the  Joint 
Committee,  State  of  Hew -York,  1912,  from  pages  933-950  where  is  given  the 
legislation  in  several  states  of  the  Union;  i'he  Bng.  Eecord  Jan.  6,  1912 
for  a  glance  at  the  legislation  on  Dams  in  some  of  the  other  States  of  the 
Union*  the  Eng.  Hews  of  June  27,  1912,  for  the  greatest  demands  of  the 
Conservation  Commission  in  the  State  of  New  York;  Uhe  Eng.  News,  April  6, 
1916  where  the  Pennsylvania  Water  Supply  Commission  announces  more  severe 


55 


rules  in  addition  to  those  of  the  Law  of  1915  passed  "by  the  State  of  Penn. ; 
the  Engl  Hews,  May  28,   1917,   the  vigilance  of  the  State  of  Connecticut   in 
regard  to  Dams.     And   thus  though  it    is  a  little  arduous,   one  can  get  an  idea 
of  the  approximate  situation  of  the   laws  in  the  U.   3.  of  the  Union  in  regard 
to  Dam  Construction. 

These  laws  are  felt  even  in  the  States  of  the  Bar  West  where  lately 
even  more  rigorous  ones  have  come  up. 

In  the  State  of  California,  the  California  Reclamation  Board,  adding 
to  the  already  severe  law  of  1915,  considered  insufficient  as  regards  Dam 
constructions,  adds: 

"The  Reservoirs,  as  regulators  of  mter  necessary,   or  as  means  of 
hydraulic  power,  or  as  a  means  of  holding    water  for  aqueducts  are  stiurces 
of  potential  grave  danger  for  the  inhabitants  and  for  the  property  situated 
below  the  Dam,     Such  a  Reservoir  gives  rise  to  a  most  dangerous  peril*     If 
the  dam  should  break,  the  downward  flow  of  the  water  that  would  be  precipitate 
into  the  valley  below  in  a  few  hours  might  be  ten  or  twenty  timesthe  normal 
maximum,  an  increase  sufficinntly  great  to  realize  it  as  destroying  life  and 
property.     The  Reclamation  Board  asks  special  powers  and  special  laws  that  wil 
sanction  the  putting  into  jail  any  one  who  through  carelessness  or  through 
desire  of  gain  violates  the  law  and  places  in  peril  the   lives  of  people  in  . 
the  valleys  below  the  dam  as  well  as  the  property  in  the  same  valley." 

$he  Department  of  State  Engineers  in  California,   insists  on  specifying 
even  more  severe  punishment.     They  show  that  the  law  of  1915  compelling  the 
use  of  perfect  plans  is  not  enough.     They  point  out  the   fact   that  a  large 
Constructing  Firm  was  constructing  in  such  a  way  that   the  work  was  defective, 
and   imperilled  the  lives  of  hundreds  of  persons  living  in  the  valley  below 
dam.     I  recall  two  clauses  that  are  as  follows:- 

1st.   That  all  Inspectors  working  for  the  State  Engineers  must  make  a 
complete  and  exact  report  on  the  quality  of  w»rk  done,   and  the 
progress  of  the  work  done  on  the  Dam  over  which  the   Inspector  has 
charge.  Any  false  report  shall  be  considered  by  law  a  felony". 


56 


2nd.  "That  any  Inspector  who  permits  "knowingly  the  violation  of  any 
clause  in  a  contract,  or  fails  to  report  the  same  shall  be 
guilty  of  felony".    (Eng.  News  Record,   Oct.  4,   1917.) 


Urges  Better  State  Supervision  of  Bams. 

California  with  an  area  of  410,000  sq.  kilom. ,   almost   1  1/2  that  of 
Italy,  had   in  the   last  half  of  the  century     a  population  of  185,000  thousand 
in  1900  -  1,  485,000   (a  density  of  3.6  to  the   sq.  fell.)  and  in  1910  had 
2,378,000   (5.8  to  the   square  kilometer). 

T-ne  result  of  State  interference  were  quickly  and  easily  seen.     In  the 
last  years  there  has  been  a  great  advance  in  the  kind  of  work  done  by  private 
individuals  in  the  construction  of  dams.     The  technical  periodicals  describe 
plans  under  consideration,   and  work  in  course  of  construction  by  firms  and 
by  private  enterprise  that  are  of  as  great  and   solid  construction  as   the 
work  done  by  the  State*     The  State  interference  is  visible  even  in  the  most 
desert  regions,   as  may  be   seen  by  the  chronicle   in  the  "Eng.  News  Record" 
Aug.  2,   1917. 

A  rancher  of  the  Far  7/est  had   started,    in  a  small  mountain  pass  of  his 
ranch,  an  arched  cement  dam  with  peculia  modifications  of  his  own.     The  Water 
Master  of  that  district   suggested   that  he  consult  an  engineer,   and  then 
obtain       the  approval  of  the  State  Engineer.     The  rancher  responded   that  from 
the  solitude  of  his  ranch,   that  he  had  constructed  a  cement  stable  in  Spokane, 
and  that  no  yellow-legged  engineer  could  teach  him  how  to  construed  a  Dam.#l 
The  Water  Master  had  him  arrested.     A  few  days  later,   the  Dam  which  was  not 
far  along  in  construction,  was  swept  away  by  an  increase   in  the   flow  of  the 
water  in  the  creek  where  the  dam  was  situated. 

I  quote  at  last   from  the  publication  of  Lof  and  Rushmore  "Hydro  Electric 
Power  Stations",  XTew  York,   1917  from  pages  88  antfard,   the  followingj- 

"Genreal  Inherent  Regulations  frflnplans  of  Bams  for  the  State  of  Hew 
York  by  the  Hew  York  State  Conservation  Commission"  which  I  have  a  reason 
for  remembering  as  being  of  1917  at  least  not  before  1916. 


57 


They  are  general  regulations  but  as  a  wnole,  even  in  my  translation, 
which  is  a  little  superficial,  they  are  full  enough  of  instructions  to  give 
an  idea  of  tne  severe  punishment  given  to  those  who  take  any  peculian 
license  with  plans  for  the  construction  of  dams. 

Among  the  most  evident  points  I  will  refer  only  to  these :- 

•Dhat  the  Hew  York  State  Conservation  Commission  exacts  the  presentation 
of  complete  plans,  examines  the  calculations  in  a  centralized  way,  undertakes 
a  first  cisit  to  the  places  selected,  and  after  the  preparation  of  the  base 
of  the  foundation,  as  well  as  (luring  the  course  of  the  construction,  assuring 
to  the  State  and  to  the  Public  a  thorough  and  competent  examination  of  all 
points  of  construction,-  and  above  all  enforces  a  uniform  law  which  is  the 
only  conceivable  requirement  for  such  undertakings. 

2hat  in  the  State  of  New  York  the  winters  being  as  severe  as  those  of 
our  Alps,  (See  special  Reports  of  U.  S.  Weather  Bureau)  serious  notice  must 
be  taken  of  the  ice-pressure  which  reduced  the  capacity  of  the  Reservoir  to 
about  1/2  or  less,-  that  much  being  all  that  can  be  useful  in  winter,-  for 
the  Dam  cannot  be  counted  on  under  these  conditions. 

It  is  from  these  comparisons  of  a  climate  resembling  that  of  the  Alps 

for  the  severity  of  its  winters,  that  I  want  to  take  data  to  form  normal 

• 

deductions  as  to  the  effect  of  ice  on  the  Dams  of  the  Alpine  Hegions,- 
statistical  effects  concerning  Dams  in  general,  and  specially  dangerous  on 
the  layer  of  cementation  in  a  supposed  lock  Dam. 

The  laws  deal  with  Cement  Dams,  Concrete  Dams,  Earth  Dams,  those  of 
hydraulic  fill,  small  Crib  or  Uimber  Dams  filled  with  rock,-  but  they  are 
silent  on  the  subject  of  Rock  Dams  unknown  in  application  outside  of  the 
Western  ^tates,  where,  let  us  state,  their  use  is  relatively  small  in  the 
High  Dam  $ype. 

(iBBBral  Rules  Governing  the  Plans  for  Dams  in  the 

State  of  New  York. 
(Given  out  by  the  Ju.  Y.  State  Conservation  Commission). 


58 


"The  complete  plans  with  tlie  elevations  and  the  sections  of  all 
proposed  Dams  must  be  submitted  and  approved  by  this  Commission  before  any 
work  whatsoever  can  be  undertaken  on  the  dam.  'i'he  location  must  also  be 
examined  and  approved  by  this  Commission  both  before  and  after  the  plans 
are  made." 

Base  of  the  Foundations. 

ihe  Dams  must  be  constructed  on  a  solid  bed  compact,  impervious,  and 
suitable  for  a  foundation.  From  such  a  foundations  must  be  removed  all 
matter  subject  to  deterioration.  The  "ground11  base  must  be  fixed  and 
drained  with  trenches.  The  wall  must  be  carried  down  into  the  solid  rock 
at  the  base  and  sides,-  wherever  possible  sufficient  indentations  will  be 
cut  into  the  rock  to  assure  a  solid  hold  for  the  Dam  itself.  The  Rock 
foundation  must  be  freed  from  all  hidden  matter.  FOP  a  distance  of  200  ft. 
above  the  top,  and  100  ft.  below  the  surface  level  of  the  Dam,  all  cracks 
«mst  be  carefully  filled  with  concrete,  or  with  grocet;  besides  this  the 
entire  surface  of  the  dam  must  be  washed.  Masonry  Dams,  more  than  35  ft. 
(about  10  meters  high),  must  have  the  rock  base  perforated  and  tested  with 
compressed  air  for  any  hidden  fissures;  these  holes  must  be  filled  with 
compressed  cement  under  a  pressure  equal  to  the  ultimate  pressure. 
Calculations: 

The  Dams  must  be  stable  in  every  section  and  under  all  conditions.  The 
pressure  on  the  Masonry  of  the  upstream  face  shall  be  10-14  and  18  tons 
per  square  foot,  according  to  the  Dam. 

IShe  first  number  (10)  is  for  walls  of  less  thickness  than  12  ft.  and 
for  buttressed  dams.  The  last  number  (18)  is  for  dams  of  compact  masonry 
rising  to  a  height  a  little  above  150  ft.  (about  45  m) ;  the  whole  executed 
as  pe  rfectly  as  possible  under  the  direction  of  a  competent  engineer 
whose  nomination  shall  be  approved  by  this  Commission.  The  cement  must  all 
be  of  Portland  "quality"  and  must  respond  to  the  standard  set  by  the  laws 

concerning  construction  in  New  York  City;  it  must  be  tried  out  as  the 


A.S.C.E.  prescribes;  any  empty  spaces  must  be  filled  with  the  proper  pro- 
portion of  sand  and  rock.  The  sand  must  be  clean  and  of  the  best  quality,- 
and  the  rock  used  for  cement  must  be  healthy,  resistant,  and  hard,-  and 
not  easily  split  or  broken. 
Vents: 

All  the  Bams  snail  be  provided  with  outlets  of  sufficient  dimensions 
so  situated  as  to  permit  the  retained  water  to  be  freed  when  it  is  desired 
or  necessary;  every  precaution  must  be  used  to  prevent  any  leakage 
through  the  said  outlets. 
Pressure  of  the  Ice: 

From  Dec.  1st  to  March  15th  no  dams  shall  have  more  than  2/3  of  the 
height  of  the  Dam  itself  filled  with  water,-  unless  the  Conservation 
Commission  has  given  permission  to  keep  the  water  at  a  higher  level.  All 
Dams  that  are  liable  to  be  full  during  the  stated  winter  period  must  be  so 
calculated  I  constructed)  as  to  resist  the  ice  pressure  in  addition  to  the 
water  pressure.  All  Dams  not  planned  this  way  must  have  a  free  outlet  2/3 
of  the  distance  up  the  Dam. 
Foundation: 

All  the  outlets  and  overflows  of  the  Dams  must  be  provided  with  drains 
(plateej  or  other  structure  on  the  valley  side  of  the  Dam,  so  that  any 
damage  to  the  Dam  from  the  downfall  of  water  may  be  prevented. 
Wooden  Dams: 

Wood  Dams  can  be  used  only  for  temporary  construction,  or  where  the 
amount  of  water  in  the  lake  does  not  reach  over  30  ft.,  or  where  the  depth 
of  the  reservoir  is  not  over  10  ft.  'Dhe  wood  of  the  Dam  must  be  renewed 
every  five  years  unless  a  permission  is  granted  by  the  Conservation 
Commission  for  a  longer  period.  2!he  crib-work  of  wooden  dams  must  be  made 
in  pockets  not  more  than  8  ft.  square,  and  well  neld  together  with  cross- 
beams or  bolts  or  not  less  than  3/4  in.  and  long  enough  to  pass  through 
three  layers  of  wood;  the  pockets  must  be  carefully  packed  with  stones. 


60 


The  upstream  face  of  the  Dam  must  toe  built  at  an  incline  of  3  horizontal 
to  1  vertical.  It  snail  be  covered  with  a  bulkhead  over  which  shall  be 
spread  an  abundant  layer  of  gravel  or  coarse  sand.  If  the  foundation  is 
of  rock,  the  wood  must  be  placed  securely  in  the  rocfc  itself. 
Earth  Bams: 

She  upstream  half  of  earth  dams  shall  be  composed  of  gravelly  earth 
with  at  least  15/o  of  clay,  and  with  no  rock  more  than  4  in.  near  the  up- 
atream  side,  or  if  there  be  a  core,  next  to  the  core  on  the  upstream  side. 

The  earth  must  be  moist  but  not  wet,  well  placed  in  layers  of  12  inches 
slightly  inclined  toward  the  middle  of  the  Dam.  The  half  toward  the  valley 
or  the  part  below  the  interior  nucleus  can  be  composed  of  material  and  stone 
less  fine.  The  top  of  the  Dam  must  be  slightly  convex  and  of  a  minimum 
width  of  8  ft.  and  1  ft.  more  in  width  for  every  5  ft.  above  15  ft  in 
height.  The  inclination  of  the  walls  must  be  2  horizontal  for  1  vertical; 
if  the  upper  part  is  made  of  the  finest  material  obtainable,  the  slope  may 
be  less. 

A  berme  or  horizontal  surface  which  will  be  not  less  than  4  ft.  wide 
will  be  placed  horizontally  on  the  walls  every  2Q  ft.  below  the  top.  On  the 
down-stream  side,  these  bermes  should  be  provided  with  paved  drains.  The 
upstream  side  will  be  paved  with  rock  of  18  inches  from  the  top  of  the  Dam 
to  the  highest  benne,  and  farther  down  paved  with  "rip-rap".  Every  Earth 
Dam  shall  be  provided  with  an  overflow  in  masonry  of  sufficient  capacity  to 
allow  the  flow  of  maximum  floods.  This  must  be  constructed  with  the  same 
care  as  in  the  Llasonry  Dams.  The  height  of  the  Dam  will  be  at  least  3  ft. 
above  the  water  surface  lovel,  3  ft.  more  if  the  water  extends  a  mile,  8  ft. 
more  for  an  extension  of  two  miles;  proportionally  for  intermediate  extension*, 

The  iiiarth  Dams  of  more  than  10  ft.  (3  meters)  in  height  will  be 
provided  with  a  central  core  of  masonry,  the  top  of  which  will  not  be  more 
than  2  ft.  with  an  increase  of  1  ft.  horizontally  for  every  24  ft.  in 
altitude  on  every  Aide;  or  the  core  itself  can  be  put  on  the  upstream  side 


in  which  case  the  thickness  of  the  core  must  equal  1/2  of  the  distance 
between  it  and  the  top  of  the  Jam,  or  else  the  core  may  be  omitted  altogether 
and  the  darn  will  then  have  to  be  5  ft.  wider  and  3  ft,  higher  than  when  it 
is  more  stable  in  construction, 
iiasonfcy  Dams: 

The  minimum  thickness  at  the  top  of  a  Masonry  Dam  will  be  1/10  of  the 
height  -  not  less  than  4  ft,  i'he  minimum  widtn  at  any  depth  will  be  2/3 
of  the  depth  under  the  maximum  level.  I'he  masonry  will  be  constructed  in 
horizontal  sections  with  central  channel  at  the  top  and  on  the  sides  made 
by  bonding  formed  by  placing  square  timbers  in  the  cement,  x'he  concrete 
masonry  will  have  vertical  bars  of  cast  iron  on  the  upstream  side  placed 
at  not  more than  2  ft.  from  each  other  in  order  to  protect  the  masonry  from 
the  ice  and  other  floating  bodies, 
Reinforced  Buttressed  Dams: 

She  buttresses  will  not  be  more  than  20  ft.  (6  meters)  apart  for  Dams 
having  more  than  100  ft,  in  height  (30  meters)  on  a  foundation  in  the  rock. 
She  buttresses  will  be  nearer  for  other  Dams,  They  will  have  the  necessary 
main  Gross-beams  to  sustain  them.  The  upstream  side  will  make  an  angles  of 
not  more  than  45  degrees  with  the  horizontal,  and  the  dovmstream  side  not 
more  than  60  degrees.  No  part  of  the  Dam  can  have  a  width  of  less  than  12  in. 
If  the  Dam  is  on  a  rock  foundation,  the  front  side  will  have  a  big  cut-off 
wall  built  into  the  rock.  If  the  foundation  is  of  gravel  or  clay  betv/een 
the  two  surfaces  there  must  be  a -deep  cut-off  wall  and  a  strong  reinforced 
f loori  ig  with  openings  for  a  drain  to  lessen  the  pressure  of  the  water  under 
the  said  flooring.  She  drainage  must  be  provided  with  interior  pockets  for 
the  water  that  filters  through.  If  possible,  the  interior  should  be 
accessible  to  allow  inspecting.  The  top  of  the  overflow  and  for  three  ft. 
be^ow  must  be  greatly  increased  and  reinforced:  the  entire  dam  and  its 
bulkheads  will  be  protected  from  ice  and  floating  bodies  as  in  the  Masonry 
Dams.  The  Dam  must  be  strongly  anchored  to  its  bulkhead. 


62 


7,   Place  of  France  and  Switzerland  in  the  Argument. 
Italian  Precedence. 

Suitable  places  for  secure  or  safe  dams  are  not  frequent. 
The  Removal  of  deceiving  elements  during  the  Inquiries. 

The  Statistical  Report  in  its  correlation  with  the  vastness  of  oronydro- 
graphy  is  better  explained  when  it  is  spoken  of  as  having  its  origin  in 
Sv/itzerland.  There  was  a  beginning  of  a  propaganda  started  in  1912  by 
Eng.  Killias.  Not  only  did  it  have  no  sign  of  a  following  in  any  discussion 
that  I  Imow  of  in  Switzerland,  but  neither  did  it  have  in  France  which  has 
also  a  section  of  60,000  sq.  kilom.  in  the  Alps.  Switzerland  and  France  do 
not  know  of  the  use  of  Rock  Dams.  FQr  Switzerland  it  would  be  the  Dam  of 
Biscnina  in  the  Gauton  of  Ticino,  about  which  the  Scritti  Luiggi  started  a 
false  account:-  but  the  humble  little  dyke  is  not  of  rock,  although  of  the 
Highest  type  of  dry  masonry",  has  a  neight  of  12%5  meters,  and  is  deeper 
only  for  a  few  meters  in  the  gorge,  and  much  less  deep  in  the  remainder  of 
the  entire  length  of  46  meters.  It  has  a  covering  of  from  1  meter  to  .40 
of  a  meter  of  hydraulic  walling  at  the  base,  made  of  rough-cast  cement. 
This  moaest  little  dyke  did  not  expect  to  be  made  the  standard  bearer  for 
the  campaign  in  fatfor  of  High  Rock  Dams,  as  the  pure  type  wanted  by  the 
Scritti  L.L.  Even  in  the  Report  of  the  original  constructing  Engineer 
Nezzola  (Sept.  10,  1911)  this  was  not  suspected  or  hinted  at. 

The  same  telescopic  growth  of  facts  and  circumstances  occurs  in  connect io: 
with  the  Propaganda  of  the  "Established  Procedure  in  Italy"  (Scritti  L.  L. 
N(4)  page  17-19)  in  regard  to  the  "Dry  Masonry"  of  the  Oeniscnio  (Lake 
d'Alpone)  and  the  Devore  Dam.  This  is  a  good  construction  of  the  highest 
type  of  "dry- masonry"  containing  within  its  limits  more  than  would  be 
justified  by  prudence.  The  retaining  capacity  will  reach  20  meters,  (about) 
when  important  plans  will  be  worked  out  to  increase  the  efficiency  of  the 
outlest,  strengthen  the  solidity  of  the  Devero  Dam,  and  raise  it  to  a 
height  of  30  or  31  meters,  including  the  one  point  of  equivocation  which 


63 

leads  the  -uninformed  reader  into  error,-  that  of  counting  the  height  of  a 
Dam  of  this  type  from  the  depth  of  the  "tali on"  on  the  wall  which  goes  up 
to  the  plane  of  support  of  the  construction^  page  134) 

2he  situation  in  France  concerning  the  problem  of  Reservoirs  gives  a 
reason  for  expounding  a  consideration  which  we  regard  as  urgent  and  important 
and  which  was  inspired  by  the  daily  experiences  of  the  Council. 

Often  the  gentlemen  Projectors  are  led  by  an  enthusiasm  due  to  the 
deceiving  merits  of  an  exhibition  of  comparative  current  plans,  leading  them 
into  technical  fallacies  on  the  subject  of  Reservoirs;  the  one  who  writes 
is  a  warm  but  reasoning  partisan. 

Any  immense  cavity  can  become,  for  too  many  Projectors,  the  basis  of  a 
Reservoir,  the  sign  of  any  gorge  can  become  the  starting  point  of  a  most 
daring  Dam.  Competition  starts  with  the  noting  of  valleys  that  have 
reservoirs  and  it  is  easy  to  try  and  rival  one  another  for,  always,  on  the 
map,  the  highest  Dams  have  collected  the  greatest  amount  of  water*  Concerning 
the  construction  experience  of  my  Country,  which  up  to  this  time  has  been 
qftite  limited,  there  has  been  brought  to  me  a  most  vivid  impression  of 
certain  facts,  very  precisely  exposed  byt  very  crudely  too,  -  in  a  notice 
dated  "Rome"  in  the  "Genio  Civile"  of  May  16,  1918.  2his  notice  was  written 
by  a  colleague  whom  I  do  not  know,  Signer  Toscani,  but  who  is  known  as  a 
constructor  of  note  on  account  of  the  part  he  has  taken  in  the  construction 
on  the  Dams  of  Lake  Delio,  of  Brasimone,  or  Gorfino,  of  Muro  Lucano,  and  on 
account  of  his  study  of  the  OJirso  Dam.  In  his  censure  of  work,  there  are 
seen  fragments  of  truth  that  are  still  in  great  part  not  revealed  in  works  of 
general  technique:  they  have  a  biting  conclusion  to  teach  caution,  specially 
in  regard  to  the  chief  requisite  condition  of  having  the  foundations  well 
secured  in  rock.  Those  few  pages  merit  the  serious  consideration  of  us  all. 
He  says  openly  and  sincerely  that  the  search  for  localities  adapted  for 
reservoirs  is  not  an  easy  search  and  often  not  positively  sure. 


64 

To  technicians  and  expert  geologists  especilly  as  regards  the  high 
moral  responsibility  that  will  result  to  them,  knowing  as  they  do  the 
requisites  that  must  be  exacted  everwhere,  America  included,  in  regard  to 
Dams  and  to  the  placing  of  Dams,-  with  well-measured  words  1  want  to  say 
that  the  verification  of  the  Posts  or  Sections  must  correspond  to  the  moral 
responsibility,  must  be  carried  out  without  hesitation  to  a  most  conscientious 
degree,  because  the  consequences  of  an  error  or  a  doubt  may  be  incalculable 

in  the  future  more  or  less  distant  but  fatally  certain. 

/ 
Where  the  Water  Problems  of  Reservoirs  have  already  been  seriously 

considered,  the  ultimate  conclusions  agree  with  those  already  reached,. 

Our  Colleague,  Eng.  Paul  Levy  Salvador,  Head  of  the  French  Technical 
Farming  Water  System,  expert  partisan  of  the  argument,  on  account  of  his 
high  office,  writes,  "(riven,  the  Utility  of  the  Kesergoirs,  it  seems  that 
they  should  exist  in  large  numbers,  in  the  high  mountain  valleys.  The  reality 
for  many  reasons  is  far  from  this  specially  because  favorable  places  for  the 
erection  of  big  Darns  in  narrow  gorges  are  most  rare".  (Societe  df Encouragement 
pour  I1 Indus trie  Nationale,  Paris,  1916.) 

The  same  conclusions  have  been  reached  after  serious  researches  in  the 
Eastern  Alps  section. 


Let  us  move,  then,  in  the  interest  of  our  Country,  with  the  greatest 
possible  activity  in  the  search  for  suitable  places  for  the  erection  of 
Reservoirs  that  have  the  means  for  a  secure  Dam.  Let  us  try  to  find  a  way 
of  taking  away,  or  at  least  of  attenuation  the  illusion   of  a 
great  result,  greater  .than  the  real  result  obtainable,  an  illusion  brought 
about  during  the  competition  for  various  locations  of  Plants,  certain  ones 
of  which  are  dangerous  when  contrasted  with  more  serious  and  pruuent  plans. 
One  must  be  very  careful  because  very  often  there  creep  into  these  compara- 
tive plans  elements  that  are  misleading  and  that  will  be  inevitably 
disastrous  in  the  future.  Such  elements  are  deceiving  and  even  when 


65 


suspected,  cannot  always  be  detected. 

For  such  reasons,  it  seems  to  me  that  it  is  the  function  of  the  State 
to  select  a  Council  wnich  should  give  prompt  and  certain  aid  to  local 
investigation  using  primarily  specialists  in  geology  wlio  understand  t he 
necessary  conditions  for  constructing  Dams,  wno  are  made  Functionaries  of 
the  State,  and  who  have  a  full  knowledge  of  their  responsibility.  2!he 
example  of  the  American  State  Conservation  Commission  is  worth  examining.  I 
barely  outline  a  plan  that  can  be  followed  by  the  proposed  Commission, 
at  the  end  of  this  Report. 

8.   An  Overflow  is  fatal  to  Rock  Dams* 

Schuyler's  Most  Important  Decree  forgotten  in  Practice. 

Itfs  confirmation  in  the  Lower  Otay  Da$. 

Fortunate  Escape  of  the  Llorena  Dam  and  Escondido  Dam. 

Remedies  for  these  and  for  the  Strawberry  Dam. 

There  does  not  exist  a  method  of  calculation  for  Rock  Dams. 

Important  iiesults  and  Opinions  of  the  American  Discussion  of  1916. 

turning  to  the  inherent  defects  of  a  Rock  Dam,  I  notice  that  the  most 
vital  problems  in  this  xype  have  been  touched  upon  in  tnue  terms  by  Schuyler 
in  the  original  edition  of  "Reservoirs  for  Irrigation,  (1897)  which  gave 
Wegmann  and  many  othersinf ormation  when  they  were  recording  the 
bibliography  of  Bock  Dams. 

Coming  to  a  particularly  grav.e  public  disaster,  the  break  of  the 
Walnut  Rock  Dam,  1890,  Schuyler  expounds  the  following  conclusion:- 

lf!Phe  most  important  lesson  than  can  be  gotten  from  this  event  is  that 
in  no  case  is  it  prudent  to  allow  the  highest  water  level  in  a  Bock  Dam  to 
go  over  the  crest  of  the  said  Dam  in  any  measure,  and  that  it  is  absolutely 
necessary  to  provide  ample  discharges  for  the  greatest  possible  exits  of 
water  without  letting  it  get  even  approximately  near  the  height  of  the  top 
of  the  dam. (18th  Annual  Report  of  the  U.>j. Geological  Survey,  page  722). 


66 


As  I  have  already  said  and  will  specify  again,  this  condition  which 
compels  one  to  turn  to  the  "Maximum  possible  ocCurence"  is  for  a  quantity 
which  it  is  difficult  to  judge  of  because  it  is  always  a  seriously 
uncertain  one. 

To  base  the  estimate  on  .a  maximum ; deducted  from  a.  brief  or  an 
insufficient  period  leads  and  has  led  to  great  errors*  Cromwell,  Engineer 
of  the  City  of  San  Diego,  after  the  destruction  of  the  Lower  Otay  notes  that 
the  unit  maximum  of  the  highest  water  level  of  any  previous  period  was 
surpassed  seven  times  at  the  time  of  the  disaster •  In  America  the  volumes 
of  the  Water  Supply  Papers  give  at  the  time  every  notable  point  of  a  great 
hydrographic  plot  not  only  the  simple  hydrometrical  height  but  also  a  list 
of  efficacious  defluctions.  Such  a  knowledge  is  lacking  for  95$  of  our 
national  area. 

Rectifying  several  errors  of  preceding  critics,  Engineer  Gromwell  adds,- 

"I  know  several  reports  made  about  the  water  system  of  the  City  by 
able  hydraulic  engineers  called  in  for  a  consultation  in  regard  to  the 
development  and  the  capacity  of  the  system  itself.  They  expressed  it  as 
their  opinion  that  it  was  improbable  that  the  Reservoir  of  Lower  Otay 
would  fill  itself  with  water  from  its  own  basin  to  even  the  level  of  the 
overflow  which  is  11  ft,  (3.35  meters)  below  the  top  of  the  Dam. 

It  seems  cruel  that  the  Omnipotent  should  not  inform  us  a  few  weeks 
ahead  of  time  when  He  intends  to  send  us  a  deluge  such  as  the  one  that 
raged  into  this  basin  on  Jan.  27,  1916,  (Eng.  News  April  13,  1916).  In 
regard  to  the  last  hypothesis,  I  will  say  that  the  Reservoir  surprised  by 
such  a  downpour  while  still  12  ft.  below  the  overflow  level  could  easily 
have  emptied,  first  of  all'1. 

2    ihe  Morena  Dam  was  miraculously  saved  only  because  the  Reservoir,  at . 
the  beginning  of  the  heavy  rains  was  in  exceptionally  empty  condition,  so 
much  so  that  at  the  most  terrible  moment  of  the  cloud-burst,  at  seven  o'clock 
in  the  morning  on  Jan.  27,  1916,  and  after  several  days  of  violent  water 


,67 


fall,  the  level  in  the  Reservoir  was  still  at  138  l/£  ft,  (42.24  meters)  the 
top  of  the  Dam  "being  150  ft.  so  that  the  last  terrible  down-pour  remained 
at  the  highest  water  level  only  18  inches  (0.4572  meters)  under  the  crest 
of  the  Dam. 

If  the  Reservoir  had  not  been  "exceptionally  empty11  even  by  a  little 
bit,-  the  Ohief  Engineer  of  San  Diego  says  (Eng.  News  Dec.  14,  1916).  If 
the  height  of  the  water  at  7  A.M.  Jan.  27.  1916,  had  been  only  three  feet 
higher,  141.5  ft.  instead  of  138.5  ft*,  it  would  inevitably  have  been 
completely  filled  and  would  have  overflOY/ed  the  top  of  the  Dam  as  happened 
at  the  Lower  Otay" 

Here  follows  textually  the  Report :- 

"It  is  impossible  to  state  what  the  consequences  would  have  been  if  a 
considerable  quantity  of  water  had  flowed  over t he  top  of  the  Morena  Dam, 
but  there  is  one  serious  question  involved  which  cannot  be  answered, 
whether  the  Dam  could  have  stood  under  such  conditions. 

$he  Morena  ^am  is  a  type  of  Hock  Construction  not  built  to  withstand 
the  overtopping  as  would  an  overflow  type  of  dam. 

It  might  have  resisted  such  a  condition,  but  we  have  not  the  right  to 
say  it  would  $ave,  which,  according  to  me,  would  not  be  a  wise  statement". 

All  the  others  (and  I  cite  the  Eng.  Record  of  June  10,  1916,  on 
account  of  its  excellent  note)  and  the  distinguished  California  Engineer 
George  Binckley  of  Los  Angeles  have  concluded  that  the  Morena  Dam  was 
"masvelously  saved",  or  had  a  narrow  escape.  They  all  recommended  a 
great  reform  in  efficiant  overflow  discharges. 

In  regard  to  the  Morena  Dam,  in  the  Report  of  the  "Documents  of  the 
A.3.C.E.  1912,  the  Constructor  0'Shaughnessy  did  not  give  any  special 
indications;  requested  to  make  it  clear,  he  adds  to  the  discussion  that  the 
highest  water-level  measured  on  the  same  Cottonwood  Creek  below  the  Moreaa 
Dam  at  Barret,  where  the  basin  is  250  eq.  mi.  (647.5  sq.  k. )  haa  had.  about 
7000  cu.  ft.  (about  198  cu.  m. )  so  that  at  the  location  of  the  Morena  Dam 


68 


with,  a  Reservoir  having  a  capacity  of  l£  billions  of  gallons  (57  million 

cu.  m. )  and  with  a  basin  of  only  1.36  sq.  miles,  the  Author  had  full  confidence 

in  the  sufficiency  of  the  v/ater  flow.   (loc.  cit.  page  64). 

Facing  the  fact  that  a  water-level  of  more  than  the  supposed  maximum, 
and  after  the  extraordinary  escape  of  the  enormous  Reservoir  wnose  ruin 
would  nave  produced  a  terrible  disaster,  it  is  only  natural  that  a  sudden 
increase  for  the  water  flow  has  been  added  to  all  the  most  recent  dams. 
(Eng.  Hews,  Dec.  14,  1916. 


It  is  also  a  significant  fact  that  for  the  Strawberry  -^am  (while  the 
particulars  are  lacidLng  in  the  .ueport  of  Constructing  Engineer  Howson, 
Eng.  News,  March  30,  1916,  edited  probably  before  the  Lower  Otay  Disaster) 
in  the  already  mentioned  description  of  the  Eng.  Kecord  of  Aug.  26,  1916, 
there  is  given  a  new  way  to  measure  the  flow  capacity  by  flash  boards,  and 
it  mentions  that  the  flow  capacity  will  be  four  times  that  of  the  greatest 
defluxion  recorded  on  the  basis  dominated  by  the  Dam,-  significant  prudence 
which  one  might  say  is  excessive,  and  which  is  materially  impossible  in 
our  Country. 

Concerning  the  Strawberry  Dam  which  was  not  far  advanced  in  construction 
in  the  summer  of  1916,  there  is  not  another  single  later  notice* 


At  the  same  time,  in  attempting  to  remedy  the  few  Rock  Dams,  notably 
in  the  Western  America,  the  truth  is  that  they  had  to  turn  to  the  dictates 
of  Schuyler.  (Dhis  action  finds  its  definite  sanction  in  the  Discussion  of 
the  event  of  Jan.  27,  1916,  concerning  the  Lower  Otay  Dam,  the  sources  of 
which  have  already  been  specified  in  paragraph  3  and  to  which  we  refer  as 
to  the  vest  part  of  the  meager  bibliography  on  Rock  Dams. 

A  few  inexact  facts  are  corrected  in  the  course  of  the  Discussion.  A 
few  favorable,  brief  signs  are  drawn  up  in  the  Eng.  Mews  which  have  already 


69 

been  combated  recently  and  overcome  in  the  same  Eng.  Mews  and  in  the  Eng. 
News  Kecord  by  other  circumstances  than  those  of  the  disaster  so  minutely 
written  up  in  the  ting*  neoord  of  i-eb.  12,  iyi6  by  Engineers  whose  worth  is 
already  known,-  nearly  all  Californiana.  Tnese  men  bring  to  the  periodicals 
the  technical  tneories  of  the  u.  o.,  the  echo  of  thoughtsand  of  numerous 
local  articles  that  we  would  not  notice,  'i'he  ting,  JUOWB  of  tfeb,  10,  and  of 
March  9,  1916,  tend  rather  to  exonerate  this  type  of  construction,  and  to 
put  the  blame  on  the  material  used  in  the  walls  of  the  Bam. 

Let  us  turn  to  Kalph  Bennet  of  Los  Angeles,  California. (Eng.  News, 
March  9. ) 

"It  seems  that  you  want  to  suppose  that  the  down  stream  side  of  a  itook 
Dam  if  covered  with  blocks  of  stone  can  stand  the  overflow  from  the  defluxion. 
I  do  not  beliave  it  a  correct  theory,  or  a  practice  suitable  to  this  Hock 
type  to  allow  a  discharge  on  the  back  of  such  a  structure." 

Follows  an  acute  analysis  to  which  as  always  I  refer,  confirming  among 
other  things,  that  the  calculations  of  the  stability  of  iiock  Dams  are  of 
very  little  significance. 

The  suggestions  of  Sellew  and  others  to  exact  besides  an  absolute 
condition  of  no  overflow,  o/ther  coefficients  of  security,-  3,5  or  better, 
4  against  a  slipping  of  the  base  —  are  useful  suggestions.  Other  well-known 
California  Engineers  such  as  Jorgensen  (written  on  Discussions  and  Heports 
on  Arched  Dams)  Bennett,  Binckley,  affirm  with  sincerity  that  there  is  no 

• 

way  of  calculating  for  such  a  structure,  #1 

Bennett  shows,  among  other  things,  how  the  penetration  on  the  water 
into  the  body  of  a  liock  .uam  due  to  overflow  gives  rise  to  new  conditions 
resulting  from  loosening,  sinking  and  displacement,  Sohuyler's  prejudice 
against  Hook  Fill  Dams  becomes  justified. 

More  forceful  still  is  the  note  to  which  Horace  King,  the  illustrious 
Engineer  and  Professor  in  Michigan  University  refers,  Deferring  to  the 
brief  notice  in  Eng.  wews  of  Feb.  10,  1916,  he  says: 


70 

"Rock  Dams  are  adaptable  to  certain  localities  in  the  western  part  of 
the  U,  3.  and  for  rivers  flowing  through  rock  canons  where  the  material  for 
an  Earth  Dam  is  scarce,  and  the  cost  of  constructing  a  Masonry  Dam  is 
prohibit ive". 

Then  follow  notices  of  the  applicability  to  "certain  parts  of  the 
Western  u.  o."  which  accentuate  still  more  efficaciously  what  has  been 
noted  concerning  the  conditions  of  a  vast  region  almost  deserted  and  of 
great  hydraulic  power,-  conditions  very  different  from  tnose  of  the 
Eastern  U.  S.  and  very  different  indeed  from  those  of  Italy. 

The  Chief  Engineer  of  the  City  of  San  Diego,  Cromwell,  who  writes  in 
the  ii;ng.  i.ews  of  Apr.  13,  1916,  rectifies  in  his  report  several  important 
former  errors,  in  his  letter  of  karch  23rd.: 

"Of  all  the  discussions  concerning  this  break,-  the  Articles  of 
Jorgensen  and  of  Horace  jxing  are  the  most  important,  and  it  is  tnese  that 
approach  the  truth  more  than  any  article  I  have  seen". 

Cromwell  concludes: 

"She  break  was  due  to  the  overflow  because  the  flow  capacity  was 
insufficient  for  such  a  high  water-level,  higher  than  any  preceding.  However, 
I  do  not  think  that  any  engineer  in  the  whole  country  would  have  recommended 
a  larger  flow  capacity  judging  from  the  measure  registered  of  previous 
rainfalls  before  the  recent  violent  storm. " 

Another  precious  i*ote  that  contains  acute  observations  and  to  which  I 
refer,  is  given  by  the  California  Engineer  E.  i'rask  in  the  Eng.  ivews  of 
May  25,  1916.  The  note  reveals  the  condition  by  wnich  another  Hock  Dam  was 
barely  saved,-  the  j^sc'ondido  Dam  also  in  Southern  California.  It  was  planned 
by  'i'rask.  The  .Notes  tnrow  light  on  some  truths  that  are  not  even  mentioned 
in  the  Scritti  Luiggi,  and  in  those  of  his  followers.  We  touch  some  points 
of  great  importance  in  respect  to  the  criticism  and  construction,  avoiding 
tuus  the  least  doubt  in  regard  to  the  technical  side,  interesting  in  itself, 
but  here  secondary:- 


71 


"The  7th  of  July,  1890,  the  writer  being  a  Consulting  Engineer  in  the 
District  of  Escondido  Irrigation  System,  stated  that  he  counseled  the  building 
of  a  iiock  Dam  in  the  place  where  it  v/as  later  built.  During  the  recent 
torrent  of  Jan.  1916  this  Dam  had  an  overflow  of  two  inches  (5  centimeters) 
at  the  t\vo  ends,  and  of  more  in  the  center  where  for  a  distance  of  60  ft. 
(18  meter  s)  the  excess  was  12  inches  (30  cm.).  The  rock  fill  lowered  in 
some  places  1  ft,  and  a  small  quantity  was  displaced  on  the  down-stream  side. 
That  this  structure  is  still  standing  is  due  only  to  the  fact  that  the  body 
of  the  dam  was  composed  of  strong  frlocks  with  large  spaces  free  from  sand, 
earth,  clay  etc. 

"It  is  well  to  re.-nember  that  the  disintegration  of  tne  mass  of  the  rock- 
fill  in  this  type  of  dam  is  always  talcing  place  with  the  result  that  the 
settling  and  adjustment  of  the  whole  mass  and  of  the  interior  mass,  produce 
a  tendency  in  the  whole  structure  to  slip  toward  the  down-stream  when  it  is 
subjected  to  the  increasing  pressure  produced  by  the  rapidly  rising  water  in 
the  Reservoir.  Above  all,  I  maintain  that  Hock  Fill  Dams  never  should  be 
used  where  there  is  an  overflow.  The  writer  wishes  to  call  attention  of 
engineers  to  the  great  breaks  in  the  mountain  canons  of  Western  America, 
i'hese  immense  hog-back  Dams  of  rock  broken  in  past  geological  days,  have 
slid  into  the  canons  of  the  adjoining  mountains  and  have  completely  barred 
the  canon  and  have  created  lakes  or  reservoirs,  in  some  cases,  thousands  of 
feet  deep.  In  all  cases  known  to  the  writer,  these  natural  rock-fill  dams 
have  been  broken  by  the  overflow  of  water,  and  have  been  broken  like  real 
dams  notwithstanding  the  fact  that  the  cross-section  is  much  stronger  than 
that  of  any  artificial  construcion  ever  made.  The  lessons  of  the  sliding 
in  the  two  Hock  Fill  Dams  of  California,-  the  Escondido  and  the  Lower  Otay, 
are  of  great  value  and  can  be  resumed  briefly  thus: 

Rock-dams  should  not  ever  be  constructed  unless  tney  are  safe-guarded 
"by  a  generous  use  of  spillway  that  assures  the  structure  against  overflow. 


In  these  Dams  only  rocks  of  crystal  formation,  hard  and  durable,  and  in  large 
blocks  free  of  fine  material,  should  be  used.  These  Dams  should  be  designed 
with  a  coefficient  against  the  slipping  of  not  less  than  3.5  v/ith  a 
protecting  wall." 

There  follows  in  the  same  paper  a  notice  of  a  new  type  of  Gravity 
Masonry  Dam  proposed  for  the  San  Diego  Otay  Valley  by  the  sane  O'Shaughnessy 
(Bng.  News,  Aug.  3,  1916)  who  on  account  of  the  varied  ups  and  downs  of  the 
Morena  Dam,  augments  greatly  the  number  of  outlets.  (Eng.  i^ews  Dec,  14,  1916), 

More  brief  but  important,  and  equally  deadly  in  it  conclusions,  is  the 
review  in  the  Eng.  Rec.  of  Feb.  12,  1916  which  starts  a  complete  minute 
description,  and  wxiich  nas  the  remarkable  description  of  the  California 
Engineer  George  Mnckley  (to  whose  writings  I  refer  you,  not  having  had  the 
time  to  translate  the  entire  discussion  as  it  should  be  translated)  where 
it  is  decided  again  that  the  overflow  is  the  only  real  cause  of  the  break 
in  the  Lower  Otay,  and  where  are  given  acute,  original  conceptions  about  the 
character  of  the  structure  made  of  an  amassing  of  stone,  and  about  the 
ruinous  effect  of  the  penetration  of  the  overflow  water  in  the  Body  of  the 
Hock  Dam, 

9.   Secondary  Arguments  relative  to  the  Propaganda, 
!Bhe  disintegration  of  the  Materials. 
The  Over-pressure. 
The  Foundations. 
Heat  Variations. 

(Che  decisive  facts  exposed  by  the  planner  of  the  Escondido  Dam,  Trask, 
show  that  overflow  means  disintegration  and  settling  in  the  interior  of  the 
dam  even  when  constructed  with  large  blocks  of  exceptionally  hard  rock,  as 
in  the  Escondido  Dam.  With  great  reason  we  can  infer  that  in  time  the  rock 
will  become  less  solid  as  the  "mica-Shist"  so  cotiiraon  in  our  Alps. 

The  Scritti  Luiggi  give  other  arguments  against  the  Cement  Dams,  the 


73 

decay  of  such  structures  that  are  of  a  monolithic  type,  but  they  do  not 
mention  that  the  type  they  advocate  on  which  the  many  factors  of  disinte- 
gration are  operating,  become  disintegrated  much  more  quickly. 

The  disintegration  in  the  case  of  rfcck  not  exceptionally  hard  must 
destroy  with  time  the  lower  layers  of  the  Dam,  if  they  are  not  more  compact 
than  those  whose  porosity  allows  free  infiltration  of  the  water, 

This  tneme  is  connected  with  that  of  the  under  support  which  is 
erroneously  considered  as  not  existing  in  the  Hock-Fill  type:  it  is 
connected  with  that  of  the  foundations  considered  with  inexcusable  indulgence 
in  the  Scritti  (N  4  page  25)  while  in  every  example  of  the  High  American 
Dams  is  placed  the  condition  of  Aoining  with  a,  protecting  wall  the  firm 
rock  under  the  wnole  circumference*  But  the  development  of  these  conceptions 
that  are  found  in  the  arguments,  much  debated  and  difficult,  of  the  under 
support  and  of  the  penetration  of  water  into  the  body  of  the  Dam  through  the 
natural  surface  at  the  foundation,  might  take  us  too  far  away  from  the 
immediate  object  of  this  Note*  They  can  be  explored  elsewhere,  for  instance 
in  an  immediate  argument  by  the  Commission  appointed  to  study  concerning 
Dams  in  general*  Here,  it  would  be  a  development  out  of  place  and  dispropor- 
tionate to  the  scheme  of  the  assertion  made  by  the  Scritti  Luiggi, 

The  Thermic  argument  about  cement  dams,  the  last  topic  in  tha  Scritti 
L.L.,  is  another  propaganda  in  favor  of  Rock  Darns*  While  at  first  it  does 
not  appear  so,  it  is  Jiot  at  all  comprehensible: 

"On  the  Italian  Dams  barring  the  valleys  turned  toward  the  North  the 
sun  does  not  beat  directly  on  the  side  facing  down  stream,  and  that  facing 
up  stream  for  the  greater  part  of  tne  year  is  immersed  in  the  waters  of  the 
Lake  and  does  not  feel  greatly  the  variations  of  temperature.  The  result  is 
that  the  phenomenon  of  the  contraction  and  dilation  of  the  wall  cut  off  at 
Assuan  passes  almost  unnoticed  in  the  Italian  Wall  Dams.  (Scritti  L.L. 
H  (3)  page  20  of  the  Estratto). 


Instead  the  thermic  report  is  repressed.  It  would  not  be  out  of  place 
to  glance  at  the  geograpnic  and  climatic  condition  of  the  place  where  at 
great  heights  with  an  exteraemly  small  climatic  extreme,  and  where  springs 
are  unknown,  they  build  and  will  continue  to  build  in  our  valleys  grand  and 
magnificent  Gravity  Dams  of  ceuemt  or  Arched  Dams  without  there  ever  being  a 
trace  of  a  Kock  Dam.  It  will  be  enough  to  refer  to  the  report  of  the  U.  S. 
Weather  Bureau  for  precise  information  on  climatic  conditions.  The  report 
of  1908  by  Bigelow  on  the  climate  of  the  U.  3.  with  an  annexed  chart  is  very 
comprehens  ive . 

10.  Eeport  on  the  Security  of  iiock  Fill  Dams  and  the  Provision  of  a 
Spill\vay  Capacity. 

The  Character  of  absolutely  the  Greatest  Occurence. 

Main  Difference  between  Our  Kainfail  and  lliiat  of  Western  America. 

Conditions  of  the  Problems  in  the  Alps  and  the  Apennines. 

Turning  to  the  fundamental  point,  we  must  consider  the  overflow  as  the 
great  destructive  force  in  Rock  Dams  as  shown  in  the  settling  and  the 
displacements  that  are  due  to  breaks  in  the  thin  mantle  that  covers  the 
walls,  the  intervention  of  destructive  factors  already  mentioned,  water, 
and  the  height  and  velocity  of  the  escaping  jets  of  water. 

This  being  settled,  ±  remember  the  examination  of  the  recent  "Instruttari; 
whose  allusions  already  }jave  revealed  to  me  how  the  idea  of  covering  the 
external  walls  with  blocks  to  prevent  dangers  by  overflow,  was  regarded 
officially.  Such  a  presumption  cannot  endure  after  being  well  explained 
and  after  the  advertisement  made  of  it  in  complete  description. 

The  first  condition  for  the  existence  of  a  itock-Fill  Dam  depends  on 
the  flow  capacity.  But  this  decisive  matter  is  considered  with  inconsequented 
ease  while  any  other  matter  (theme)  would  be  considered  after  firm  reflection. 

A  dam  that  lasts  four,  five,  ten  years  is  a  ^am  that  "functions  well". 
Such  judgment  has  no  sense  in  it.  It  is  not  deduced  from  a  specific 


75 

examination  of  the  construction  but  made  simply  because  the  structure  had 
stood  four,  five,  ten  years. 

Above  all,  the  water  manifestations  that  in  a  long,  a  very  long  time,, 
can  produce  the  gravest  disaster,  are  looked  at  very  differently  from  those 
that  have  already  been  seen  and  commented  upon.  An  occurrence  that  may  be 
fatal  is  looked  at  as  far,  frery  far  away,  in  fact  in  every  place  where  one 
has  not  spcific  data  to  depend  upon,  one  trusts  to  intuition  concerning  the 
construction,  But  there  are  other  causes  that  bring  about  the  deterioration 
of  the  construction.  I  speak  of  the  under-support ,  the  slow  penetration  of 
the  water  by  pressure,  a  cause  potentially  active  from  the  beginning  bjft  whic] 
works  continuously  year  after  year,  and  which  finishes  only  when  the 
structure  is  destroyed. 

Now  we  come  inevitably  to  the  "greatest  extraordinary  event",  and  I 
confess  that  first  motive  of  the  "Scritto :  of  mine  concerning  the  essential 
nature  of  Kock-tfill  Dams  is  (L.H.P.  to  express)  my  mature  thought  and 
experience  on  that  which  to  us  signifies  the  most  terrible  accident,  the 
maximum  discharge  of  the  water  from  a  basin  of  given  sixe  in  a  given  region 

But  then  it  could  be  easily  claimed  that,  being  in  accord  on  the  subject 
of  overflow  in  a  Rock  Kill  Dam  is  equal  to  its  destruction,  it  will  suffice 
to  make  the  flow  capacity  ample  enough  to  guarantee  it  from  the  unexpected 
by  large  margins  of  safety,  say  by  two  to  four  times  the  greatest  noted  water- 
level,  as  has  been  done  in  the  cases  of  Otay,  Morena  and  ^trawberry  Dams  in 
California  as  the  result  of  experience  had  in  Rock  Dams. 

Instead  this  point  is  another  theme  upon  which  current  thought  finds 
an  insufficient  knowledge  of  facts. 

If  one  considers  value  and  the  distribution  of  rain-fall  in  North 
America,  e.g.  on  the  chart  of  Henry  in  the  U.  S.  Weather  Bureau  for  the 
period  1870-1901,  or  in  the  more  recent  one  by  Gaunet,  U.S.  Weather  Bureau 
(,,.3.  Paper  234)  or  better  still,  in  the  already  mentioned  work  of  Bigelow 
(U.S.  Weather  Bureau)  it  is  shown  that  in  El  Dorado,  with  few  noted  Hock  Dams 


76 

(situated  partly  in  South,  and  partly  in  Central  California)  the  greatest 
part  of  the  area  has  an  annual  rain-fall  of  from  0  to  10  inches  (0  to  25 
centimeters] •  At  an  altitude  of  about  1000  meters  in  the  Morena  Beservoirs, 
a  report  of  (J'Shaughnessy  (Documents  of  the  A.3.C.E.  Aug.  1912)  gives  for 
five  years  an  annual  rainfall  of  from  a  minimum  of  13  inches  (33  centimeters) 
to  a  maximum  of  35  inches  (89  cm).  Thus  in  the  immense  region  of  the  Far 
Y/est,  the  greatest  part  has  an  annual  rainfall  of  from  0  to  10  in,,  a  small 
part  10  to  20  in.,  and  a  very  small  part,  a  little  more. 

Without  referring  now  to  2  1/2  and  3  1/2  meters  in  some  notable  sections 
of  the  Alps  and  Apennines  we  will  consider  only  the  meter,  and  a  half  or 
less,  in  the  interior  sections  of  the  Alps  and  Apennines,  it  is  easy  to  see 
that  if  in  America  a  secure  excess  of  from  2  to  4  times  the  possible  maximum 
of  the  water-level  is  sufficient,  it  is  difficult  to  estimate  practically, 
and  almost  impossible  to  provide,  such  protection  in  our  countries. 

She  maximum  possible  discharge  in  reference  to  a  square  kilometer  of  a 
basin  of  area  A  in  square  kilom.  is  a  problem  not  only  in  regard  to  all  the 
climatic  and  plastic  elements  of  the  basin,  but  also  of  the  size  of  A 
specially  as  tJae  boundaries  of  A  are  Of  interest  as  applied  to  Reservoirs. #(1) 

All  this  is  general,  as  there  is  not  present  data  applicable-  research 
exacts  special  study  for  every  case.  There  is  nothing  certain  for  all  cases. 
Thus  until  a  few  years  ago,  •*•  thought  that  a  discharge  of  9  or  10  cubic  meters 
to  the  square  kilometer  was  possible  only  in  certain  section  of  the  Ligurian 
Apennines  having  basins  of  only  a  few  square  kilometers. 

The  study  for  the  city  of  G-enoa  of  an  extraordinary  cloud-burst  that 
dev-;.staed  the  estern  Hiviera  at  the  end  of  1915,  showed  me  that  a  discharge 
of  10  to  lid  cu.  meters  per  second  to  the  sq.  kilom.  is  possible.  The 
number  deducted  by  careful  investigation  and  from  direct  study  was  very 
little  talked  about,  wnile  a  distinguished  Ministerial  Commission,  basing 
its  estimates  on  the  data  of  rainfall  and  on  conventional,  but  fallacious 
hypotheses  on  the  distribution  reached  numbers  that  were  three  times 


77 

greater  than  mine. 

In  one  of  our  Central  Alpine  basins  of  6,000  sq.  kilom.  it  was  materially 
possible  in  a  memorable  event,  to  have  a  discharge  of  2  cu.  meters  per  second 
to  the  sq.  kilom.  as  the  average  in  the  basin.  In  another  hi^n  water-level, 
it  was  possible  to  have  a  discharge  of  3  cu.  meters  per  sq.  Icilom.  in  a 
basin  of  about  1600  sq.  kilom.  (Bacino  Dell  *0ssola  of  the  Val  Toce).  These 
figures  show,  as  possible,  a  discharge  of  at  least  5  or  6  cu.  meters  per 
sq.  km.  in  a  small  basin  of  10  sq.  k.  even  out  of  the  zone  most  exposed  to 
heavy  rainfalls. 

In  fact,  two  erudite  colleagues,  interested  or  present  in  two  different 
places  of  the  said  Ossolance  Valley,  assured  me  that,  in  the  cloud-burst  that 
struck  the  Alpine  Valley  of  the  Ossola  last  month,  June  1918,  with  violent 
S.E.  winds,  the  diacharge  had  a  force  of  200  cu.  meters  in  an  Alpine  basin 
of  30  sq.  km.   lAlta  OvescaJ  i.e«  2  1/2  cu.  meters  per  sq.  km.,  and  a 
discharge  of  5  or  6  cu.  m.  for  every  sq.  km.  of  the  basin  of  only  a  few  sq. 
km.  of  Lake  Vaunnio  in  an  aosolutely  Alpine  section  at  an  altitude  of  over 
2,200  meters;  numbers  which  the  undersigned  already  presumed  to  criticize 
personally  on  account  of  the  highest  level  of  the  Toce  more  directly 
affected  by  the  S.E.  winds.  All  this  leads  to  an  argument  hardly  great 
enough  to  merit,  for  any  length  of  time,  the  attention  of  all  the  volunteer 
observers  that  conclude,  being  intimately  acquainted  with  the  facts,  and  by 
reason  of  the  bond  existing  between  the  rising  of  the  water  and  Kock  Dams, 
that  a  certainty  or  at  least  a  probability  of  a  disaster  exists. 

Shis  must  strengthen  the  remembrance  of  how  the  same  argument  of  an 
absolute  maximum  xevel  is  treated  in  the  "Instruttarie"  in  an  entirely 
inadequate  manner,  almost  as  plans  for  ordinary  times  are  treated. 

My  impressions  are  not  like  those  of  the  Promoters,  but  I  must  bow  to 
a  most  honorable  opposition  of  the  Ministerial  Commission.  This  Commission 
in  regard  to  the  Southern  slopw  of  the  Alps,  Rosa  Group,  in  regard  to  little 
basins  10  to  14  sq.  km.  for  use  in  plans  for  Kock  Dams  was  "of  the  opinion 


76 


that  a  flow  capacity  of  1  cu.  m.  per  sq,  km,  can  be  adopted  in  calculating  tfc 
quantity  of  water  wnen  full  to  overf lov/ing" • 

The  greatest  security  against  any  specil  emergency  is  a  doubling  of 
the  outlet.  But  it  is  certain  "that  the  greatest  possible  maximum  can  be 
retained  by  having  an  outlet  at  least  four  or  five  times  "that  fcf  1  cu, 
meter"  which  the  Honorable  Commission  considers  sufficient, 

She  "limit  of  the  possible"  conceived  in  this  case  is  not  considered 
in  regard  to  climatic  conditions  more  or  less  ordinary  but  in  conjunction 
with  the  "entire  regional  absolute  possibility",  that  is,  in  a  long  period 
during  which  there  is  no  extraordinary  happening,  such  as  cloud-bursts  from 
the  S.  E,  winds,  in  that  particular  valley,  particular  direction,  or 
particular  little  basin, 

therefore  these  intense  discharges  of  at  least  4  or  5  cu,  m,  per 
second  per  sq.  tan,  in  the  small  basins  are  a  measurement  already  confirmed 
by  occurrences  in  the  Central  Alps  region  which  I  am  considering  at  this 
time.  No  one  can  tell  what  the  "maximum  absolute"  will  be  in  the  immense 
cycle  of  all  sorts  of  combinations  and  of  weather  interferences,  be  it  in  1 
year,  10  years  or  50  years.  All  I  can  do  is  to  repeat  much  of  the  material 
and  of  the  precious  contributions  offered  by  those  who  observe  carefully  — • 
the  engineers,  local  agents  of  the  Plants,  etc. 

For  19  years  that  the  Lov/er  Otay  existed,  the  precise  statistics  of 
San  ^iego  had  well  established  the  unit  of  maximum  water-level,  and  the 
level  had  never  been  surpassed  in  the  Heservoir,  until  there  came  an  event 
which  raised  the  level-unit  seven  times  more  that  the  maximum  of  the  19 
years  preceding, 

SKROR,  the  fatal  crime,  is  not  the  fact  itself.  It  lies  in  the 
person  who  considers  that  such  an  extraordinary  event  can  be  confined  in 
the  experimental  basin  of  19  years;  it  is  sufficient  to  consider  what  such 
an  occurrence  as  the  great  meteroic  event  means  in  a  historic  way,  e.g. 
Take  Lake  Maggiore  which,  in  1868,  reached  a  higher  water-level,  -  twice 


79 


as  nigh  as  had  "been  knownthere  in  the  100  years  preceding. 

11.  Conclusive  Allusions  to  Rock  Dams. 
A  Proposition  to  Revise  the  Outlets. 

A  Proposition  for  the  ^tudy  of  the  ^eneral  Problems  of  Dams, 
and  of  the  inherent  Rules. 

Now,  in  all  these  water  problems,  one  can  fortunately  single  out  the 
maximum  absolute  from  the  relative  maximum;  thus  one  can  admit  the  fact  that 
a  net-work  of  the  sewerage  overflows  into  the  street  three  or  four  times  in 
30  years.  It  can  be  admitted  that  the  Reservoir  of  a  City  Aqueduct  does  not 
correspond  to  its  contents  two  or  three  times  in  20  yearsj  that  the  canaliza- 
tion works  in  a  City, on  account  of  torrents  and  under  great  pressure, 
rejects  its  water  once  in  50  years  etc. 

Instead  in  the  special  case  of  itock  -^ams,  on  account  of  the  cruel 
correlation  between  the  two  terms,-  overflow  and  ruin,-  the  absolute  mavirmim 
is  a  condition  that  cannot  be  overlooked,  because  a  Dam  that  can  last  only  30 
years  will  not  fce  acceptable  to  anyone,  un  account  of  the  technical  uncertain 
ty  of  such  an  estimate,  even  when  estimated  with  greatest  knowledge  and  care, 
I  am  opposed  to  the  application  of  such  structures  in  Italy. 

ttbia  structure,  which  is  in  great  minority  or  hardly  used  in  the  Far 
West,  which  is  relatively  deserted  and  where  its  life  seems  almost  expended, - 
cannot  dominate  our  populous  valleys,  with  no  plastic  comparisons  in  the 
climatology,  as  I  think  I  have  shown  with  sufficient  notice. 

I,  who  deprecate  the  use  of  Rock  Dams  at  the  bottom  of  a  given  precipi- 
tous opening  more  or  less  thickly  populated  like  our  valleys,  would  admit 
thAir  use  if  situated  at  50  km.  further  in  where  it  would  cross  a  deserted 
valley,  and  where  the  terrible  force  of  the  water  during  a  break  could  be 
fairly  well  attenuated.  (Page  1^5)  (2) 

But  the  application  of  these  remedies  and  of  these  margins  of  security 

for  the  flow-capacity  S  or  4  times  the  known  maximum,  that  can  be  used  in 


80 

California,  cannot  ue  used  in  our  courty  where  the  rainfall  is  generally 
five  or  ten  times  greater,  and  where  the  unit  of  the  water-level  is  notably 
and  exceptionally  high  for  our  small  Apennine  and  Alps  basins. 

This  reason  is  sufficient  in  itself  for  my  decided  aversion  to  dock. 
Dams,  especially  as  propounded  in  the  ocritti  Luiggi,  but  it  is  not  the 
only  one.  Among  others  shown  in  the  present  report,  is  a  lack  of  faith  in 
the  durability  of  the  cer.ient  layer  spread  on  the  upstream  side  of  a  Hock  Dam 
in  the  case  of  a  break  or  fracture  due  to  the  interior  displacement  of  the 
rock  mass  caused  by  an  overflow. 

The  greatest  danger  for  this  cement  covering  in  artificial  lakes  subjecte 
to  long  periods  of  low  temperature,  resides,  in  my  opinion,  in  the  localiza- 
tion of  the  great  horizontal  strain  v/hich  occurs  at  certain  times,  and,  in 
the  more  rigorous  wintersn  by  the  existence  of  a  powerful  pressure  due  to 
ice  in  the  Reservoir. 

The  action  is  localized  along  an  undetermined  strip  of  the  thin  cement- 
covering,  and  cannot  help  but  become  dangerous,  eventually  beginning  a 
fracture  which  will  end  in  a  terrible  disaster. 

2hese  actions  which  have  a  special  effect  on  all  Rock  Dams  also  have 
an  important  effect  on  all  Dams  in  Alpine  lakes.  This  "ice-pressure"  is 
considered  very  dangerous,  and  the  State  of  New  York,  where  there  are  no 
high  altitudes  but  where  the  temperature  is  low,  has  made  very  severe  laws 
to  m;et  this  danger •  The  temperature  there  is  as  low  as  that  of  most  of 
our  Alpine  sections,-  20  to-40  degrees  tfahs.  (-20  to-40  degrees  Cent).  It 
is  quite  different  in  California.  Central  and  Lower  California  have  an 
absolute  minimum  of  10  to  30  degrees  tfahr.  (-12  to  1  Cent.) 

Shis  thermic  study,  which  1  hardly  stop  at  here,  shows  many  things, 
among  them  that  the  Morena  and  Escondido  Dams,  as  well  as  similar  ones  in. 
S.  California,  cannot  be  compared  with  those  of  our  Alps  nor  yet  with  some 
of  the  Apennines. 

We  need  a  greater  information  in  regard  to  these  arguments.  Already 


81 


they  say  in  the  most  important  recent  number  of  the  "Instruttoria",  in 
regard  to  Hock  Dams,  that  the  water  collected  in  the  frozen  Alpine  lakes 
"cannot  evidently  increase  the  hydrostatic  pressure  of  the  stored  water. 

I  think  I  have  justified  the  point  mentioned  in  paragraph  2  about  the 
merits  of  a  technical  propaganda  animated  no  doubt  by  good  faith,  but 
according  to  my  view,  most  perilous  in  its  tangible  effect  in  the  future,  on 
account  of  the  high  position  held  by  my  most  honorable  and  zealous  opponent. 

I  dedicate  these  Notes  to  the  Coundil  invested  with  such  a  great 
responsibility,  but  at  the  same  time  I  destine  them  also  to  the  technical 
public,  because  J  deem  it  necessary  and  urgent  to  prodeed  in  this  way. 

These  Notes  have  not  only  a  negative  conclusion  most  disagreeable  to 
the  great  amount  of  capital  invested  at  present;  but  they  also  nave  several 
positive  conclusions  that  appear  in  the  reading,  and  through  attentive 
comparison. 

They  have  two  important  immediate  possibilities  which  certainly  have 
already  been  sufficiently  illustrated  in  all  that  precedes:  to  these 
correspond  my  two  following  propositions: 

1st.  The  demand  of  a  revision  of  all  the  outlets  in  Rock  Dams,-  a  demand 
to  be  prepared  specially  by  the  Council  by  whom  permission  to 
construct  has  already  been  civen.  There  is  no  difficulty,  according 
to  my  opinion,  that  should  prevent  the  correcting  of  a  defect  which 
will  insidiously  cause  a  grave  disaster  in  time. 

2nd.  The  demand  for  a  special  Commission  to  examine  the  subject  of  High 

Dams  in  relation  to  work  to  be  done  by  the  State.  A  small  Commission 
composed  of  some  of  our  own  scientists,  of  othersfrom  the  Superior 
Council  of  the  L.L.P.P.,  and  from  the  Hoyal  Geological  Office,  and 
also  a  few  foreigfc  technologists  to  the  said  Council,  who  will  have 
specil  scientific  knowledge  on  the  problem  of  constructing  Dams. 

The  final  aim  must  b«  to  find  standard  laws  for  the  plans  and  constructs 
of  such  works.  May  special  important  investigations  can  be  carried  on, 
which  I  cannot  specify  here  because  of  the  lack  of  space  in  the  Notes, 
but  which  are  indicated. 

In  such  technical  constructive  investigations,  the  water  criterion 


M 

gives  decisive  warning  against  purely  statistical  construction  such 
correlations  between  pure  statistics  and  the  material  that  must  be  reckoned 
with,  are  sometimes  very  poorly  defined  even  in  the  most  thorough  collections 
of  Statistical  calculations  for  the  structures. 

There  is  a  demand  for  standardization.  I  make  mine  the  vote  of  the 
brilliant  Professor  Ganaillo  Guidi  in  regard  to  the  general  study  of  special 
specific  Italian  conditions.  (See  the  letter  in  the  Giornale  del  Genio 
Civile  of  March  1918  which  refers  to  the  number  of  Feb.  1918, ) 

•I  accept  it  but  with  a  rectification  in  the  motive  it  gives.  In  another 
interesting  debate  with  Guidi,  another  of  our  Colleagues,  the  Eng.  Forti, 
had  shown  that  all  the  disasters  recorded  by  G-uidi  in  American  were  due 
"to  the  freedom  and  the  lightness  of  construction  that  know  no  limits". 
G-uidi  objected,  fearing  the  dangerons  results  that  would  come  through  the 
importation  by  the  great  Alleato  of  the  "undertakings  of  audacious  enterprise 
These  fears  are  unjustified  and  are  excluded  because  of  the  reults  of  today. 
The  U.  S.  of  America  is  not  -what  it  is  so  often  represented  to  us,  so 
inexactly  and  so  falsely,  specially  in  regard  to  the  inherent  problem  of 
Dam  construction. 

Laws  prescribed  by  the  State  of  New  York,  and  all  other  indications 
mentioned  in  Paragraph  6  of  these  Hotes  concerning  Legislation  in  the  U.  3., 
indicate  that  the  State  Officials  in  the  U.  S.  treat  this  subject  with  the 
greatest  amoT^nt  of  severity  and  regard  it  as  a  very  important  Government 
Problem,  i'his  just  severity  does  not  forbid  high  and  daring  constructions 
but  does  not  admit  of  light  constructions  which  would  endanger  the  lives 
of  its  citizens. 

Therefore  in  this  modern  specific  theme,  of  immense  public  and  private 
concern,  the  same  noble  u.  S.  of  America  can  certainly  offer  us,  with  its 
great  fielu  for  experimentation  and  research,  much  wise  teaching,  and  be  a 
judicious,  cautions  guide. 


a; 


Milano,  July  25,  1918. 


Read  before  the  Gomitate  Permanente  del  Gonsiglio 
Superior  della  Aegue,  August  1,  1918. 


Ing,  Gandenzio  tfantoli. 


FOOT  NOSES 

Page  No.  21    See  the  Cornell  Givil  Engineer  of  Feb.  1917.  A  remarkable 

line  1 

(Orig.  p. 19)   monthly  periodical  published  by  the  Assoc.  Givil  Eng.  of 

Cornell  university. 

Page  No*  21    Notwithstanding  this  for  many  years  he  has  gotten  personally 

line  20 

Orig.  p. 19)    the  most  important  American  publications,  and  had  gotten  the 

Milan  Technical  Library  to  get  the  chief  periodicals,  Eng. 
Kecore,  Eng.  News,  Proceedings  of  A.S.C.E.,  Professional 
Memoirs  of  the  U.S.  Army,  The  Cornell  Givil  Engineer,  and 
several  others.  These  are  enough  because  all  the  technical 
matter  is  passed  in  review. 

Page  No.  63    Note  uuring  the  Printing. 

line  3 

(Orig.  p.54^   During  the  printing  of  this  Scritto  in  Milan,  Italy  and  during 

its  rading  in  Home  Aug.  1st  I  have  purposely  admitted  super- 
ficial and  different  readings  of  accessory  expressions,  leavii 
the  text  unaltered  as  it  came  from  a  rapid  editing*  Before 
sending  it  to  print,  however,  the  context  was  conscientiously 
studied  over.  If  the  form  and  lines  are  in  part  so  different 
from  what  I  should  desire,  the  sincerity  necessary  for  the 
great  work  I  have  undertaken  is  not  lacking.  I  exclude  also 
colleagues  tnrough  whom  would  have  been  given  interesting 
confirmation  of  proofs  and  of  notes  to  divers  paragraphs  of 
this  Scritto.  I  can  state  that  1  could  now  get  confirmation 
and  important  notes  from  the  "Documents  of  the  Congress  of 
International  Engineers"  held  at  S.  F.  Calif,  from  Sept.  20 
to  25,  1915.  These  Documents  which  were  printed  in  1916  and 
which  i  have  only  been  able  to  examine  this  month  contain 
another  immense  synthetic  report  on  Dams  by  A.  P.  Davis, 
Chief  Eng.  of  the  lie c lama t ion  Service  and  by  Dr.  Henny.  I 
could  take  from  the  same  Documents  interesting  and  singular 


85 

observations  concerning  the  use  of  the  hydrographic  and 
agrarian  materials  in  Italy,  and  also  concerning  the  use  of 
Rock  Dams  already  in  great  favor  in  Italy  and  in  Libia  in 
Sept.  1915, 

Page  Ho.  79    On  the  flow  due  to  breaks  in  large  iieservoirs. 

line  27 

(Orig.  p.  69)  Not  on  account  of  vain  fear,  but  to  stimulate  a  searcn  for 

greater  security  and  caution,  because  it  is  well-known  what 
a  disaster  to  one  of  the  great  constructions  of  today  would 
signify,  it  is  well  to  remember  that  with  the  breaking  of  a 
High  Dam  of  a  reservoir  of  great  capacity,  there  rushes  into 
the  valley  below,  a  flow  that,  for  some  ten  thousand  cu. 
meters  to  a  second,  lasts  several  hours  if  there  is.  a  great 
quantity  of  water  gathered,  i'he  principal  factors  in  computing 
the  discharge  in  the  section  of  a  Dam  that  is  supposed  to  be 
destroyed  are  the  height  of  the  Dam,  the  size  of  the  section 
facing  the  gorge  that  it  bars,  the  capacity  of  the  Reservoir 
or  rather  of  the  shuetto  (gate)  behind  it.  I'he  first  two 
factors  determine  essentially  the  force  of  the  flow:  it  is 
quickly  seen  how  the  break  in  a  dam  50  motors  high  with  a 
facing  on  the  gorge  of  only  2000  m.  will  act,  if  the.  Dam  breaks 
quickly,  or  jumps  like  a  being,  or  opens  lifce  the  halves  of  a 
double  door.  (Lower  Otayj .  The  effect  of  the  initial  flow  of 
10,000  cu.  met.  to  a  second  is  apparent,  i'he  third  factor 
determines  essentially  the  length  and  form  of  the  immense  flood 
of  the  discharge  due  to  the  emptying  of  the  iieservoir.  They 
are  making  what  may  seem  an  exaggerated,  but  most  interesting 
investigation  on  the  exact  importance  of  the  sections  to  a 
valley,  in  computing  approximately  the  flood  of  the  discharge  f 
(Q.T. )  when  "Q"  is  the  discharge  per  second,  the  time  "t"  of 
the  initial  break  in  the  broken  sections  and  also  in  the  sectio 


of  the  walls  facing  the  valley,  which,  were  greatly  expanded. 
They  are  considering  a  masonry  Dam  of  30  meters  in  height 
with  a  reservoir  of  five  or  six  million  cu.  meters.  The 
computation  is  not  easy,  even  with  exact  calculations  as  to 
the  maximum  velocity  of  the  water  flow.  The  Lower  Otay 
Reservoir  with  a  capacity  of  49  millions  cu.  meters,  with  a 
mediocre  retaining  wall  about  40  meters  high,  and' with  a 
narrow  canon  gorge  barred  by  it,  emptied  its  contents  in 
about  2  1/2  hours  after  the  initial  crash.  The  average  of 
the  discharge  was  5,500  cu.  meters  to  the  minute.  In  the 
first  hour  and  a  half,  the  average  unit  of  the  discharge  was 
8000  cu.  m.  to  the  second,  twice  as  muct  as  in  the  Tevera 
Dam  when  it  reaches  a  maximum  water-level. 

But  these  forces  are  sufficiently  Overcome  by  walls 
really  high  and  by  reservoirs  of  sufficient  capacity.  If 
mentally  I  deplore  the  hypothesis  of  our  Italian  conditions, 
it  is  because  I  know  that  in  general,  there  is  only  a  confuse< 
and  inadequate  idea  even  about  the  immense  floods  due  to 
defluxion  and  tq  its  presumed  destructive  effect  on  the 
surrounding  country.  If  I  do  not  hesitate  to  state  that  a 
disaster,  in  certain  places  where  great  Reservoirs  exist, 
might  be  more  than  a  local  one,  it  is  because  I  believe  in 
exercising  every  precaution,  in  calculations,  in  construction, 
in  effective  quantities  of  safety  that  cannot  be  overestimated 
especially  in  the  most  dangerous  locations, 
If  I  refer  to  the  recent  wise  decision  already  stated,  of  the 
officials  of  the  State  of  California,  which  State  iastill  far 
from  having  the  dense  population  and  the  intense  improvements 
of  our  old  soil  wherein  every  place  man  has  already  built  up 
his  own  fields,  as  says  Cattaneo;  and  if  we  refer  to  the 


87 


example  of  organization  of  the  N.  Y.   State  Conservation 
Commission,    it  is  because  I  am  convinced   that  without 
analogous  proceedings,  there  never  will  "be  found  a 
solution  to  the  problem. 

Page  No.   3  I  will  indicate  for  the  sake  of  brevity  the    sources  of 

line  19 

(Orig.p.5)  information; 

G.G.C.-  Grioraale  del  G-enio  Civile    (Journal  of  Civil  Engineerin 
A.I.I.-  Annali  della  Societa  Ingegneri  Architetti  Italian!. 
(Annals  of  the  Society  of  Italian  A rchitechtural  Engineers). 
E#R.  and  E.N.-  the  two  most   important  technical  journals 
of  engineering,-  the  Record,  and   the  Engineering  News.     These 
appear  in  large  weekly  numbers  which  were  fused  on  April  1, 
1917  into  the  precious: 
E.N.R.-  Engineering  News  Record. 

P.C.E.-  the  very  important  Proceedings  of  the  A.S.C.E.  which 
appears  monthly  with  the  discussions  of  the  x.C.E. 
Transactions  of  the  A.g.c.E. 

Page  No.   5  See  the  note  of  the  distinguished  Gamillo  (Juidi,  particularly 

line  19 

(Orig.p.7)  the  one   in  the  G.G.C,  Feb.   28,   1918  that  has  just  appeared, 

and  in  which  there  is  this  brief  paragraph  that  has  a  great 
bearing  on  the  subject  in  hand.     "And  now,   for  some  technical 
considerations.     Dams  are  divided  distinctly  into  Earth  Dams, 
Rock  Fill  Bams,  Resistant  Masonry  Dams —  like  those  of 
retaining  walls  —  and  Reinforced  Concrete  Bams. 

Those  of  Masonry  are,   according  to  Forti,   the  classic 
dams.     Those  of  specially  resistant  quality  give  the  greatest 
guarantee  for  success.     On  this  we  agree  with  him,   but  fchey 
are  now  constructing  them  of  earth  and  rock,     The  Supreme 
Council  of  Public  Works,    it    appears,   on  the  30th  of  Dec.   1916, 


81 

stated  that   It  was  right  to  construct  the  Dams  as  high  as 
possible  and  counselled  them  as  preferable   in  the   high 
mountains. 

But  moreover,   can  we  even  declare  ourselves  satisfied 
with  our  technical  taiowledge  even  in  regard  to  Masonry  Dams  ? 

Page  No.   10         U.   3.  Geological  Survey. 

line  17 

Orig.  p.   11         v/ater  Supply  Paper,   N.   395  "Colorado  River  ani    Its  Utilizatioi 

Washington  1916,  pages  12  and  22. 

?he  basin  of  the  Colorado  is  244,000  sq.  miles.     So  as  t( 
be  able  to  Ireep  the  table  measures  the  same  as  those  used  in 
the  U.S*,   I  will  give  the   following  table  for  converting  them. 
(Smithsonian  Physical  Tables,   1910  from  page  7  on).. 


JTVJJ.J.XUC      • 

PlnrH     ».,,,.  ,-_,_. 

AM.  —  • 

•ft        «    .!,.——  _- 

-   JU.     ' 

*     V/.V/fc.*^1* 
O^CtfWI  0 

-  0,9144 

.Lc&XXL 

JJd. 

~  "  4  /-H  "1  4  /I 

TTll  1  A      _ 

T?Vn 

»   1    AOQ1-? 

Miglio  Quadrate  — 

sq.  mile  — 

—  *     So.  Kin.   —  »——  — 

-  2.5900 

Piede  Cubico  —  — 

cu.   ft.  

Mr     ___..__ 

-  0.0283 

Yard  Gubico  

cu.  yd.-— 

"•^  M.  C  •   ••••••—•*-• 

-  0.7650 

Gallone  U.S.  

gall.   —  •  —  -— 

—  Litres  —  — 

-  3.7854 

Page  No.   11         For  an  approximate  idea  of  such  conditions,   see  the  usual 

line  30 

(Orig.  p.  12)       good  supports  used   in  orohydrographic  and  hypsometric  construe 

tions,  for  example,  those  of  Bartholomew,  London,  1914,  and  it 
demographic  statistics  reported  also  in  the  "Annaire  au  Bureau 
des  Longitudes",  1915  and  preceding. 

Page  Ho.   13        ?he  actual  date  because  the  number  appeared  later,   so  that  the 

line  10 

(OrJg.  p. 13)   Note  on  page  4  calls  for  Scritto  N  (5)  on  the  Strawberry  Bam, 

which  appeared  in  the  number  of  Mar.  16,  1917,  A.I.I,  an 
interesting  circumstance  for  us. 


Page  25       Arched  gravity  Dam,  cyclopean  concrete,  plums  25$  to  30^ 

line  1 

(Orig.p.  22)   Total  volume.  See  ICensico  Dam,  Eng.  Hews,  April  25,  1912- 


Page  28       See  liemoirs  of  Commissioner  of  Science  and  Letters,  of 

line  7 

(Orig.  p.   25)     Lombardy,   1917,   on  Dams;  lielazione  Fantoli. 


Page  28  See  discussion  "by  Engineer  Galloway  on  O'Shaughnessy' s 

line  18 

(Orig.  p.   25)     paper  Mo rena  Bock  Fill,  A.S.C.E.  1912.  (quotation  page  50). 


Page  29  Upper  Otay  Dam  was  a  thin  shell  of  arched  concrete 

line  7 

(Orig.  p.  26)  like  Bear  Valley  in  1900. 


Page  31       Refers  to  freedom  of  concrete  dams  from  earthquake 

line  12 

(Orig.  p.  28)  damage. 


Page  32       See  Atlas  San  Francisco  folio,  U«  S.  Geological 

line  10 

(Orig.  p.  29)  Survey,  (1914). 


Page  32       The  latter  was  uninjured  by  the  earthquake,  a  careful 

line  12 

(Orjg.  p.   29)     examination  having  failed  to  reveal  a  crack  in  the 

splendid  structure*- 


Page  39  Within  recent  years  an  new  style  of  dam  has  come  into 

line  15 

use  in  the  Western  States  of  the  Union. 


Page  40  See  Schuyler  -  Reservoirs  for  Irrigation,   1897,   and 

line  24  18th  Annaul  Report  U.S.  Geol,    Survey,  pp.   626  -  756; 

(Orig.  p.   35)     Walnut  Greek  Dam,  page  722. 


Page  41  See  Schuyler's  Hydraulic  Dams,   2nd.   edition,   1898. 

line  8 
(Orig.  p.   36) 


llote  1,  p.   59,   and  Note  1,  p.   61,    (Original)   omitted 

•?  vi     -f-  >»ovicO  Q-f-.  •?  nvt  _ 


90 


Comments  on  Professor  Fantoli 

II.  II.    0'3ILIUQHKE33Y 

I  have  read  Professor  Fantoli *s  book,   his   statements  and  quotations, 
with  a  great  deal  of  interest.     He   is  laboring  under  a  misconception  that 
any  contention  is  made  in  the  United  States  for  rock  fill  dams  that  ttey 
will  survive   flood  conditions  without  adequate  by-pass  spillways.     ITo   such 
claim  has  ever  been  made  for  rock  fill  dams  by  myself  or  any  proponent 

The  claim  is  made,  hov/ever,   that   they  will  survive  longer  than  an  earthen 
dam  when  submerged  by  overflows  over  the  top  of  the  crest* 

The  Lower  Otay  Dam,  which  failed  in  January  1916,  was  not  a  true  rock 
fill  dam,  as  it  was  full  of  muck  and  earth  all  through  the  rock,   and  when 
an  unprecedented  flood  of  30,000  second  feet  -  from  a  watershed  of  100 
square  miles  -  came,  which  submerged  the  spillway  of  only  5,000  second 
feet  capacity,   the  other  25,000  second  feet  of  flood  went  over  the  crest 
of  the  dam,  washed  away  the  slender  triangular  support  to  the  steel  plate 
core  at   the  center  of  the  Lower  Otay  dam  structure.  The  resulting  effect 
was  that  after  the  withdrawal  of  the  rock  and  earth  support  the  steel 
plates  opened  like  gates  ajar  and  the  flood  from  the  Lower  Otay  reserroir 
went  down  the  valley  to   the  Bay  of  San  Diego. 

I  examined  the  Morena  Dam  some   time  after  the  flood  and  got  the 
statements  of  the  natives  and  people  who  lived  in  the  vicinity,  also    » 
secured  photographs  of  the  condition  of  the  dam  before  flood  and  after. 
Those  photographs  disclose  the  fact  that  a  wooden  horse  runway  for  saddle 
horses  had  been  built  ac.ross  the  mouth  of  the  spillway,   120  feet  wide  by 
8  feet  deep,   in  fronljfcf  the  radial  gates  which  controlled  the  spillway 
entrance.     This  resulted  in  stopping  all  the  brush  and  trees  which  floated 
down  under  the  flood  action  of  the  storm  and  blocking  the  whole  or  75 
per  cent  of  the  capacity  of  the  spillway,  as  the  wooden  structure  was 


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directly  in  front  of  the  gates  and  squarely  across  the  spillway  channel. 
This  resulted  in  raising  the  water  in  the  lalce  so  that  it  topped  the 
crest  of  the  dam  possible  1  or  2  feet*     This  topping  had  no  effect  on 
the  Morena  Dam  as  the  water  percolated  down  through  the   roclc  structure. 
As  this  dam  was  properly  constructed  on  very  easy  slopes,  with  a  berme, 
there  was  no  soil  to  wash  away,  hence  there  was  no  failure  at  Morena. 

Hoclc  fill  dams  have  their  place  in  industrial  development  as  well  as 
masonry  dams,   earthen  dams  and  buttressed  arch  dams,  and  as   I  have  built 
types  of  each  IdLnd   successfully,    I  do  not  claim  to  be  a  proponent  of  any 
particular  type*     I  do  claim,  however,   that  a  roclc  fill  dam,  when  built  with 
care  and  workmanship,   should  survive  just  as  long  as  any  masonry  dam, 
provided  adequate  spillways  are  made  to  by-pass  the  unexpected  floods 
which  come* 

(Signed)     M.  M.   0 •  SHA.TOHEESSY 

Gity  Engineer,  San  Francisco,  California 
Civil  and  Consulting  Engineer 
October  1920 


YE  1 1 139 


